Vacuum processing chamber having multi-mode access

ABSTRACT

The case of maintainability and component replacement for a vacuum processing chamber is enhanced by providing a vacuum chamber roof assembly whose connection to the vacuum chamber body is through a clamped connection. Accessories needed for the roof assembly, e.g. cooling, heating, RF power, are separately supported and terminated to an accessories supporting cold plate, which is separately mounted such it is easily movable, for example by hinging from the chamber body. The roof of the chamber can then easily be separated from the chamber body and replaced. In an further mode the chamber roof can be easily raised to provide easy access to modular components inside the processing chamber. All components exposed to the plasma in the chamber can be easily accessed and replaced. Moreover, such access is provided without the need to disconnect utilities or instrumentation, since the release of a latch and pivoting the cold plate assembly away from the chamber body upwards is all that is needed to gain access to either the top of the roof of the processing chamber or the inside of the chamber. Chamber roof cooling is provided through a separable connection which is spring clamped to provide a high confidence that uniform thermal conductivity across a clamped joint is maintained.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/733,555 filed Oct. 21, 1996 by Kenneth S. Collins et al.entitled THERMAL CONTROL APPARATUS FOR INDUCTIVELY COUPLED RF PLASMAREACTOR HAVING AN OVERHEAD SOLENOIDAL ANTENNA, which is acontinuation-in-part of U.S. patent application Ser. No. 08/648,254filed May 13, 1996 by Kenneth S. Collins et al entitled INDUCTIVELYCOUPLED RF PLASMA REACTOR HAVING AN OVERHEAD SOLENOIDAL ANTENNA, whichis a continuation-in-part of the following U.S. applications, thedisclosures of which are incorporated herein by reference:

(a) Ser. No. 08/580,026 filed Dec. 20, 1995 by Kenneth S. Collins et al.which is a continuation of Ser. No. 08/041,796 filed Apr. 1, 1993 (nowU.S. Pat. No. 5,556,501) which is a continuation of Ser. No. 07/722,340filed Jun. 27, 1991 (now U.S. Pat. No. 5,226,932);

(b) Ser. No. 08/503,467 filed Jul. 18, 1995 (now U.S. Pat. No.5,770,099) by Michael Rice et al. which is a divisional of Ser. No.08/138,060 filed Oct. 15, 1993 (now U.S. Pat. No. 5,477,975); and

(c) Ser. No. 08/597,577 filed Feb. 2, 1996 by Kenneth Collins, which isa continuation-in-part of Ser. No. 08/521,668 filed Aug. 31, 1995 (nowabandoned), which is a continuation-in-part of Ser. No. 08/289,336 filedAug. 11, 1994 (now abandoned), which is a continuation of Ser. No.07/984,045 filed Dec. 1, 1992 (now abandoned). In addition, U.S.application Ser. No. 08/648,265 filed May 13, 1996 by Kenneth S. Collinset al. (now U.S. Pat. No. 5,859,614) entitled PLASMA WITH HEATED SOURCEOF A POLYMER-HARDENING PRECURSOR MATERIAL discloses related subjectmatter.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention is related to heating and cooling apparatus in aninductively coupled RF plasma reactors of the type having a reactorchamber ceiling overlying a workpiece being processed and an inductivecoil antenna adjacent the ceiling.

2. Background Art

In a plasma processing chamber, and especially in a high density plasmaprocessing chamber, RF (radio frequency) power is used to generate andmaintain a plasma within the processing chamber. As disclosed in detailin the above-referenced applications, it is often necessary to controltemperatures of surfaces within the process chamber, independent of timevarying heat loads imposed by processing conditions, or of other timevarying boundary conditions. In some cases where the window/electrode isa semiconducting material, it may be necessary to control thetemperature or the window/electrode within a temperature range to obtainthe proper electrical properties of the window. Namely, for thewindow/electrode to function simultaneously as a window and as anelectrode, the electrical resistivity is a function of temperature forsemiconductors, and the temperature of the window/electrode is bestoperated within a range of temperatures. The application of RF power togenerate and maintain the plasma leads to heating of surfaces within thechamber, including windows (such as used for inductive orelectromagnetic coupling of RF or microwave power) or electrodes (suchas used for capacitive or electrostatic coupling of RF power, or forterminating or providing a ground or return path for such capacitive orelectrostatic coupling of RF power) or for combinationwindow/electrodes. Heating of those surfaces can occur due to 1) ion orelectron bombardment, 2) absorption of light emitted from excitedspecies, 3) absorption of power directly from the electromagnetic orelectrostatic field, 4) radiation from other surfaces within thechamber, 5) conduction (typically small effect at low neutral gaspressure), 6) convection (typically small effect at low mass flowrates), 7) chemical reaction (i.e. at the surface of the window orelectrode due to reaction with active species in plasma).

Depending on the process being performed with the plasma processchamber, it may be necessary to heat the window or electrode to atemperature above that temperature which the window or electrode wouldreach due to internal sources of heat as described above, or it may benecessary to cool the window or electrode to a temperature below thattemperature which the window or electrode would reach due to internalsources of heat during some other portion of the operating process orsequence of processes. In such cases, a method for coupling heat intothe window or electrode and a method for coupling heat out of the windowor electrode is required.

Approaches for heating window/electrodes from outside the processchamber include the following:

1. heating the window/electrode by an external source of radiation(i.e., a lamp or radiant heater, or an inductive heat source),

2. heating the window/electrode by an external source of convection(i.e. forced fluid, heated by radiation, conduction, or convection),

3. heating the window/electrode by an external source of conduction(i.e., a resistive heater).

The foregoing heating methods, without any means for cooling, limit thetemperature range available for window or electrode operation totemperatures greater than the temperature which the window or electrodewould reach due to internal sources of heat alone.

Approaches for cooling window/electrodes from outside the processchamber include the following:

1. cooling the window/electrode by radiation to a colder externalsurface,

2. cooling the window/electrode by an external source of convection(i.e., natural or forced),

3. cooling the window/electrode by conduction to an external heat sink.

The foregoing cooling methods, without any means for heating other thaninternal heat sources, limit the temperature range available for windowor electrode operation to temperatures less than that temperature whichthe window or electrode would reach due to internal sources of heatalone.

Additionally the foregoing cooling methods have the following problems:

1. cooling the window/electrode by radiation is limited to low heattransfer rates (which in many cases are insufficient for the window orelectrode temperature range required and the rate of internal heating ofwindow or electrodes) at low temperatures due to the T⁴ dependence ofradiation power, where T is the absolute (Kelvin) temperature of thesurface radiating or absorbing heat;

2. cooling the window/electrode by an external source of convection canprovide large heat transfer rates by using a liquid with high thermalconductivity, and high product of density & specific heat when high flowrates are used, but liquid convection cooling has the followingproblems:

A) it is limited to maximum temperature of operation by vapor pressuredependence of liquid on temperature (i.e. boiling point) (unless a phasechange is allowed, which has its own problems--i.e. fixed temperature ofphase change--no control range, as well safety issues),

B) incompatibility of liquid cooling with the electrical environment,depending upon liquid electrical properties,

C) general integration issues with liquid in contact with reactorstructural elements. Cooling the window or electrode by an externalsource of convection (e.g., a cooling gas) is limited to low heattransfer rates which in many cases are insufficient for the window orelectrode temperature range required and the rate of internal heating ofwindow or electrodes;

3. cooling the window/electrode by conduction to an external heat sinkcan provide high rates of heat transfer if the contact resistancebetween the window or electrode and the heat sink is sufficiently low,but low contact resistance is difficult to attain in practice.

Approaches for both heating and cooling window/electrodes from outsidethe process chamber include heating the window/electrode by an externalsource of conduction (i.e., a resistive heater) in combination withcooling the window/electrode by conduction to an external heat sink. Inone implementation, the structure is as follows: a window or electrodehas a heater plate (a plate with an embedded resistive heater) adjacentan outer surface of the window electrode. Additionally, a heat sink(typically liquid cooled) is placed proximate the opposite side of theheater plate from the window or electrode. Contact resistances arepresent between window or electrode and heater plate, and between theheater plate and the heat sink. In such a system integrated withautomatic control of window or electrode temperature, a temperaturemeasurement is made (continuously or periodically) of the window orelectrode to be controlled, the temperature measurement is compared witha set point temperature, and based on the difference between themeasured and set point temperatures a controller determines through acontrol algorithm how much power to apply to the resistive heater, oralternatively, how much cooling to apply to the heat sink, and thecontroller commands output transducers to output the determined heatingor cooling levels. The process is repeated (continuously orperiodically) until some desired degree of convergence of the window orelectrode temperature to the set point temperature has occurs, and thecontrol system remains active ready to respond to changes inrequirements of heating or cooling levels due to changes in internalheat or cooling levels or to changes in the set point temperature.Besides contact resistance problems that limit the cooling capability ofthe system to control the temperature of the window or electrode, thesystem exhibits a time lag in transferring heat from the window orelectrode to the head sink as required when the internal heating orcooling load changes during plasma reactor operation. This is due inpart to the contact resistance between the window or electrode and theheater, and contact resistance between the heater and the heat sink, aswell as the thermal capacitance of the heater and the window orelectrode. For example, as the internal heat load is increased in aprocess or sequence of processes, the system senses the increase bymeasuring an increase in window or electrode temperature. As describedabove, the system reduces the heater power or increases the coolingpower in response to the increase in window or electrode temperature,but there is a lag time for the heat to diffuse through the window orelectrode, across the contact resistance between window or electrode andheater, through the heater plate, across the contact resistance betweenthe heater and heat sink. In addition, "excess" heat energy "stored" inthe heater diffuses across the contact resistance between the heater andheat sink. This lag causes more difficulty in controlling thetemperature of the window or electrode as the internal heat or coolingload changes, typically resulting in some oscillation of the window orelectrode temperature about the set point.

A further problem for a window or window/electrode (of the type thatallows electromagnetic or inductive RF or microwave power to be coupledfrom outside the chamber to inside the chamber via the window orwindow/electrode) is that the presence of heat transfer apparatus(heater and/or heat sinks) interferes with the coupling of suchelectromagnetic or inductive RF or microwave power, and/or the presenceof RF or microwave power coupling apparatus may interfere with heattransfer between heater and/or heat sink and window or window/electrode.

Thus a method is sought for heating and/or cooling a window or electrodeor window electrode used in a plasma processing chamber so that thetemperature of the window or electrode or window/electrode may becontrolled sufficiently close to a set point such that a desired processor sequence of processes may be carried out within the plasma processchamber, independent of the change of internal heating or cooling loadswithin the chamber or changes in other boundary conditions.

Additionally, a method is sought for heating and/or cooling a window orwindow/electrode used in a plasma processing chamber so that thetemperature of the window or electrode or window/electrode may becontrolled sufficiently close to a set point temperature, withoutinterference to coupling of electromagnetic or inductive RF or microwavepower through the window or window/electrode such that a desired processor sequence of processes may be carried out within the plasma processchamber, independent of the change of internal heating or cooling loadswithin the chamber or changes in other boundary conditions.

Additionally, a method is sought for heating and/or cooling an electrodeor window/electrode used in a plasma processing chamber so that thetemperature of the electrode or window/electrode may be controlledsufficiently close to a set point temperature, without interfering withcapacitive or electrostatic coupling of RF power, or interfering withterminating or providing a ground or return path for such capacitive orelectrostatic coupling of RF power, such that a desired process orsequence of processes may be carried out within the plasma processchamber, independent of the change of internal heating or cooling loadswithin the chamber or changes in other boundary conditions.

Additionally, a method is sought for heating and/or cooling a window orelectrode or window/electrode used in a plasma processing chamber sothat the temperature of the electrode or window/electrode may becontrolled sufficiently close to a set point temperature, withoutinterfering with capacitive or electrostatic coupling of RF power, orinterfering with terminating or providing a ground or return path forsuch capacitive or electrostatic coupling RF power, and withoutinterfering with coupling of electromagnetic or inductive RF ormicrowave power through the window or window/electrode such that adesired process or sequence of processes may be carried out within theplasma process chamber, independent of the change of internal heating orcooling loads within the chamber or changes in other boundaryconditions.

SUMMARY OF THE INVENTION

A configuration according to the invention includes a chamber forprocessing a workpiece having a multi-mode chamber service accessconfiguration. The chamber has body subunit with a pedestal defining agenerally flat surface for mounting workpiece to be processed, a chamberroof subunit removably and sealingly engageable upon the chamber bodysubunit, the roof subunit including a chamber roof extending in spacedrelationship to and along the pedestal workpiece surface when engagedupon the chamber body subunit, the roof subunit including at least oneextension (separator) member extending laterally away from the roof andaway from the pedestal. The chamber also includes a cold plate subunitremovably engageable with the at least one extension (separator) memberso as to be positioned in a spaced relationship from the chamber roof, acoil supported from the cold plate subunit so as to be positionableadjacent the chamber roof, the coil accepting RF power and capable ofcausing a plasma to be established in a gas within the chamber byinduction, a hinge assembly peripherally mounting both the chamber roofsubunit and the cold plate subunit so as to move the cold plate subunitindependently of or together with the chamber roof subunit about a hingeaxis of rotation. In a first mode, both chamber roof and cold platesubunits may be pivoted as a single assembly away from the chamber bodysubunit for access to the interior of the chamber. In a second mode, thecold plate subunit may be pivoted away from the chamber body subunitindependently of the chamber roof subunit, to allow the chamber roofsubunit to be accessed or removed from the chamber body subunit and coldplate subunit easily and immediately as well as well as to allow accessto cold plate and coil components normally facing the roof subunit. Thecold plate subunit is adapted to accept fluid circulation lines forcooling fluid and to mount RF supply connectors to enable RF power to betransmitted to the coil. The cold plate subunit includes an array ofheat lamps extending toward the chamber roof when the cold plate androof subunits are in engagement with the chamber body subunit. The coldplate subunit can mount a plurality of the coils. The chamber mayinclude a plurality of the extension (separator) members in concentricarrays. The plurality of coils the coils may be distributed andsupported so as to lie within or outside of the concentric arrays. Theextension (separator) members are made of a thermally conductivematerial. The chamber roof may be a silicon material. The extension(separator) members may be a silicon material. A layer of a thermallycompliant material may be positioned between the extension (separator)member and the cold plate and may be compressed therebetween forimproved thermal transmissibility.

In an alternative aspect of the invention, a configuration for a plasmachamber may include a plasma processing chamber roof sealed to andcreating a portion of a vacuum limit of the plasma processing chambertogether with a chamber body assembly; a cold plate disposedapproximately parallel to and offset from the roof; a plurality ofthermally conductive members creating a thermal bridge between the roofand the cold plate; wherein the thermal bridge is detachably connectedto either the cold plate or the roof, such that when the cold plate isseparated from the roof, the roof is immediately accessible, as well asthe space therebetween. The chamber may also include a hinge mechanism.The roof may be made of a silicon based material. The separation betweenthe roof and the cold plate may be as a result of the cold plate beingfixed to a hinge mechanism which causes the cold plate as it isseparated from the roof to hinge about a hinge axis, wherein the hingeaxis is fixed to the chamber body. The plurality of thermally conductivemembers may form a ring which may be fixed to the chamber roof and maybe mated to the cold plate through a compliant heat transfer material.The compliant heat transfer material may be Grafoil. The chamber mayinclude a coil which induces the plasma in the processing chamber and isfixed to and supported by the cold plate. The set of heaters/lampsdisposed to heat the chamber roof may be supported by the cold plate. Athermal sensor for sensing the temperature of the chamber roof may besupported by the cold plate. The thermally conductive members may beurged into contact with the cold plate by a set of spring members. Alift ring can be selectively attached to an chamber roof assembly, thelift ring when engaged with the chamber body causes the roof to movewith the cold plate as a unit. The cold plate is fixed through thechamber body to a hinge mechanism which causes the cold plate and roofas a unit to hinge about a hinge axis, wherein the hinge axis is fixedto the chamber body. The utilities supplied to and supported by the coldplate, are configured so that they do not have to be disconnected beforethe cold plate and roof is hinged about the hinge axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away side view of an inductively coupled plasma reactorof the type employed in a co-pending U.S. patent application referred toabove employing generally planar coil antennas.

FIG. 2 is a log-log scale graph of induction field skin depth in aplasma in cm (solid line) and of electron-to-neutral elastic collisionmean free path length (dashed line) as functions of pressure in torr(horizontal axis).

FIG. 3A is a graph of plasma ion density as a function of radialposition relative to the workpiece center in the reactor of FIG. 1 for aworkpiece-to-ceiling height of 4 inches, the curves labelled A and Bcorresponding to plasma ion densities produced by outer and inner coilantennas respectively.

FIG. 3B is a graph of plasma ion density as a function of radialposition relative to the workpiece center in the reactor of FIG. 1 for aworkpiece-to-ceiling height of 3 inches, the curves labelled A and Bcorresponding to plasma ion densities produced by outer and inner coilantennas respectively.

FIG. 3C is a graph of plasma ion density as a function of radialposition relative to the workpiece center in the reactor of FIG. 1 for aworkpiece-to-ceiling height of 2.5 inches, the curves labelled A and Bcorresponding to plasma ion densities produced by outer and inner coilantennas respectively.

FIG. 3D is a graph of plasma ion density as a function of radialposition relative to the workpiece center in the reactor of FIG. 1 for aworkpiece-to-ceiling height of 1.25 inches, the curves labelled A and Bcorresponding to plasma ion densities produced by outer and inner coilantennas respectively.

FIG. 3E is a graph of plasma ion density as a function of radialposition relative to the workpiece center in the reactor of FIG. 1 for aworkpiece-to-ceiling height of 0.8 inches, the curves labelled A and Bcorresponding to plasma ion densities produced by outer and inner coilantennas respectively.

FIG. 4A is a cut-away side view of a plasma reactor employing a singlethree-dimensional center non-planar solenoid winding.

FIG. 4B is an enlarged view of a portion of the reactor of FIG. 4Aillustrating a preferred way of winding the solenoidal winding.

FIG. 4C is a cut-away side view of a plasma reactor corresponding toFIG. 4A but having a dome-shaped ceiling.

FIG. 4D is a cut-away side view of a plasma reactor corresponding toFIG. 4A but having a conical ceiling.

FIG. 4E is a cut-away side view of a plasma reactor corresponding toFIG. 4D but having a truncated conical ceiling.

FIG. 5 is a cut-away side view of a plasma reactor employing inner andouter vertical solenoid windings.

FIG. 6 is a cut-away side view of a plasma reactor corresponding to FIG.5 in which the outer winding is flat.

FIG. 7A is a cut-away side view of a plasma reactor corresponding toFIG. 4 in which the center solenoid winding consists of plural uprightcylindrical windings.

FIG. 7B is a detailed view of a first implementation of the embodimentof FIG. 7A.

FIG. 7C is a detailed view of a second implementation of the embodimentof FIG. 7A.

FIG. 8 is a cut-away side view of a plasma reactor corresponding to FIG.5 in which both the inner and outer windings consist of plural uprightcylindrical windings.

FIG. 9 is a cut-away side view of a plasma reactor corresponding to FIG.5 in which the inner winding consists of plural upright cylindricalwindings and the outer winding consists of a single upright cylindricalwinding.

FIG. 10 is a cut-away side view of a plasma reactor in which a singlesolenoid winding is placed at an optimum radial position for maximumplasma ion density uniformity.

FIG. 11 is a cut-away side view of a plasma reactor corresponding toFIG. 4 in which the solenoid winding is an inverted conical shape.

FIG. 12 is a cut-away side view of a plasma reactor corresponding toFIG. 4 in which the solenoid winding is an upright conical shape.

FIG. 13 is a cut-away side view of a plasma reactor in which thesolenoid winding consists of an inner upright cylindrical portion and anouter flat portion.

FIG. 14 is a cut-away side view of a plasma reactor corresponding toFIG. 10 in which the solenoid winding includes both an inverted conicalportion and a flat portion.

FIG. 15 is a cut-away side view of a plasma reactor corresponding toFIG. 12 in which the solenoid winding includes both an upright conicalportion and a flat portion.

FIG. 16 illustrates a combination of planar, conical and dome-shapedceiling elements.

FIG. 17A illustrates a separately biased silicon side wall and ceilingand employing electrical heaters.

FIG. 17B illustrates separately biased inner and outer silicon ceilingportions and employing electrical heaters.

FIG. 18 is a cut-away cross-sectional view illustrating a firstembodiment of the plasma reactor having a thermally conductive gasinterface at each face of the thermally conductive torus of FIG. 5.

FIG. 19 is a cut-away cross-sectional view illustrating a secondembodiment of the plasma reactor having a thermally conductive gasinterface at the one face of a thermally conductive torus integrallyformed with the semiconductor window electrode.

FIG. 20 is a cut-away cross-sectional view illustrating a thirdembodiment of the plasma reactor having a thermally conductive solidinterface material at each face of the thermally conductive torus ofFIG. 5.

FIG. 21 is a cut-away cross-sectional view illustrating a fourthembodiment of the plasma reactor having a thermally conductive solidinterface material at the one face of a thermally conductive torusintegrally formed with the semiconductor window electrode.

FIG. 22 is a cut-away cross-sectional view illustrating a fifthembodiment of the plasma reactor in which the disposablesilicon-containing ring of FIG. 5 is cooled by a cold plate with athermally conductive gas interface between the cold plate and thedisposable silicon ring.

FIG. 23 is a cut-away cross-sectional view illustrating a sixthembodiment of the plasma reactor in which the disposablesilicon-containing ring of FIG. 5 is cooled by a cold plate with athermally conductive solid interface material between the cold plate andthe disposable silicon ring.

FIG. 24 illustrates a seventh embodiment of the plasma reactor in whichthe chamber wall and an interior chamber liner are cooled using athermally conductive gas in the interfaces across the heat conductionpaths.

FIG. 25 illustrates a modification of the embodiment of FIG. 24 in whichthe interfaces are each filled with a solid thermally conductive layerinstead of the thermally conductive gas.

FIG. 26 illustrates the embodiment of FIG. 22 in which the ring iselectrostatically clamped to seal the thermally conductive gas.

FIG. 27 illustrates a plasma reactor embodying different aspects of theplasma reactor including modular plasma confinement magnet liners.

FIG. 28 is an enlarged view of a portion of a modular plasma confinementmagnet liner, illustrating how a magnet is sealed within the liner.

FIG. 29 illustrates a heated silicon ring employed in the reactor ofFIG. 27 having a slit therethrough to permit thermal expansion.

FIG. 30 illustrates an inductive antenna employed in the reactor of FIG.27 having a uniform number of effective windings around its azimuth.

FIGS. 31A-31E illustrates different magnetic orientations for pairs ofplasma confinement magnets employed in the reactor of FIG. 27.

FIG. 32 is a schematic perspective view of an embodiment according theinvention with the chamber roof assembly, including a chamber roof, withthe roof assembly separated from the chamber body, the internal surfacesincluding the inside of the chamber roof being exposed.

FIG. 33 is a schematic perspective view of the embodiment of theinvention shown in FIG. 32, however in this view the chamber roof (itsoutside being observable) is still in place and the heat lamps, sensors,and coils attached to the chamber roof assembly can be observed.

FIG. 34 shows a top schematic view of a cold plate subassemblycomprising a part of the chamber roof assembly with the cold platesubassembly supporting the heat lamps, induction coils, and thermalsensors.

FIG. 35 shows a partial cross sectional view of a chamber according tothe invention showing the sealing arrangement at the edge of the chamberbetween the chamber roof and body assemblies, with a schematicrepresentation of the hinged connection between these assemblies.

FIG. 36 is a schematic cross sectional view of a chamber according tothe invention showing the interrelationship of pieces adjacent to thechamber roof and their support from the chamber body in a configurationwhere the where the chamber roof assembly is in a closed position withrespect to the chamber body.

FIG. 37 is a schematic cross sectional view of the configuration of FIG.36, where the chamber roof is left in position while the chamber roofassembly and cold plate subassembly or subunit is hinged away from thechamber body.

FIG. 38 is a schematic cross sectional view of the chamber roof assemblyof FIG. 36, showing the attachment of a lift ring for lifting thechamber roof in this configuration.

FIG. 39 is a schematic cross sectional view of a chamber body accordingto the invention where a lifting motion of the chamber roof has begun,by the upward motion of the chamber roof assembly, however the upwardmotion of the chamber roof assembly has caused the gap between the liftring and chamber roof to be reduced, without any motion of the roof,while further upward motion will cause the chamber roof to move (hinge)upward.

FIG. 40 is a schematic cross section showing the progression of lifting(hinging) as the chamber roof assembly along with the cold platesubassembly or subunit and chamber roof, together hinge upwards.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Disclosure of the Parent Application:

In a plasma reactor having a small antenna-to-workpiece gap, in order tominimize the decrease in plasma ion density near the center region ofthe workpiece corresponding to the inductive antenna pattern centernull, it is an object of the invention to increase the magnitude of theinduced electric field at the center region. The invention accomplishesthis by concentrating the turns of an inductive coil overlying theceiling near the axis of symmetry of the antenna and maximizing the rateof change (at the RF source frequency) of magnetic flux linkage betweenthe antenna and the plasma in that center region.

In accordance with the invention, a solenoidal coil around the symmetryaxis simultaneously concentrates its inductive coil turns near the axisand maximizes the rate of change of magnetic flux linkage between theantenna and the plasma in the center region adjacent the workpiece. Thisis because the number of turns is large and the coil radius is small, asrequired for strong flux linkage and close mutual coupling to the plasmain the center region. (In contrast, a conventional planar coil antennaspreads its inductive field over a wide radial area, pushing the radialpower distribution outward toward the periphery.) As understood in thisspecification, a solenoid-like antenna is one which has plural inductiveelements distributed in a non-planar manner relative to a plane of theworkpiece or workpiece support surface or overlying chamber ceiling, orspaced at different distances transversely to the workpiece supportplane (defined by a workpiece supporting pedestal within the chamber) orspaced at different distances transversely to an overlying chamberceiling. As understood in this specification, an inductive element is acurrent-carrying element mutually inductively coupled with the plasma inthe chamber and/or with other inductive elements of the antenna.

A preferred embodiment of the invention includes dual solenoidal coilantennas with one solenoid near the center and another one at an outerperipheral radius. The two solenoids may be driven at different RFfrequencies or at the same frequency, in which case they are preferablyphase-locked and more preferably phase-locked in such a manner thattheir fields constructively interact. The greatest practicaldisplacement between the inner and outer solenoid is preferred becauseit provides the most versatile control of etch rate at the workpiececenter relative to etch rate at the workpiece periphery. The skilledworker may readily vary RF power, chamber pressure andelectro-negativity of the process gas mixture (by choosing theappropriate ratio of molecular and inert gases) to obtain a wider rangeor process window in which to optimize (using the plasma reactor) theradial uniformity of the etch rate across the workpiece. Maximum spacingbetween the separate inner and outer solenoids of the preferredembodiment provides the following advantages:

(1) maximum uniformity control and adjustment;

(2) maximum isolation between the inner and outer solenoids, preventinginterference of the field from one solenoid with that of the other; and

(3) maximum space on the ceiling (between the inner and outer solenoids)for temperature control elements to optimize ceiling temperaturecontrol.

FIG. 4A illustrates a single solenoid embodiment (not the preferredembodiment) of an inductively coupled RF plasma reactor having a shortworkpiece-to-ceiling gap, meaning that the skin depth of the inductionfield is on the order of the gap length. As understood in thisspecification, a skin depth which is on the order of the gap length isthat which is within a factor of ten of (i.e., between about one tenthand about ten times) the gap length.

FIG. 5 illustrates a dual solenoid embodiment of an inductively coupledRF plasma reactor, and is the preferred embodiment of the invention.Except for the dual solenoid feature, the reactor structure of theembodiments of FIGS. 4A and 5 is nearly the same, and will now bedescribed with reference to FIG. 4A. The reactor includes a cylindricalchamber 40 similar to that of FIG. 1, except that the reactor of FIG. 4Ahas a non-planar coil antenna 42 whose windings 44 are closelyconcentrated in non-planar fashion near the antenna symmetry axis 46.While in the illustrated embodiment the windings 44 are symmetrical andtheir symmetry axis 46 coincides with the center axis of the chamber,the invention may be carried out differently. For example, the windingsmay not be symmetrical and/or their axis of symmetry may not coincide.However, in the case of a symmetrical antenna, the antenna has aradiation pattern null near its symmetry axis 46 coinciding with thecenter of the chamber or the workpiece center. Close concentration ofthe windings 44 about the center axis 46 compensates for this null andis accomplished by vertically stacking the windings 44 in the manner ofa solenoid so that they are each a minimum distance from the chambercenter axis 46. This increases the product of current (I) and coil turns(N) near the chamber center axis 46 where the plasma ion density hasbeen the weakest for short workpiece-to-ceiling heights, as discussedabove with reference to FIGS. 3D and 3E. As a result, the RF powerapplied to the non-planar coil antenna 42 produces greater induction[d/dt][N·I] at the wafer center--at the antenna symmetry axis46--(relative to the peripheral regions) and therefore produces greaterplasma ion density in that region, so that the resulting plasma iondensity is more nearly uniform despite the small workpiece-to-ceilingheight. Thus, the invention provides a way for reducing the ceilingheight for enhanced plasma process performance without sacrificingprocess uniformity.

The drawing of FIG. 4B best shows a preferred implementation of thewindings employed in the embodiments of FIGS. 4A and 5. In order thatthe windings 44 be at least nearly parallel to the plane of theworkpiece 56, they preferably are not wound in the usual manner of ahelix but, instead, are preferably wound so that each individual turn isparallel to the (horizontal) plane of the workpiece 56 except at a stepor transition 44a between turns (from one horizontal plane to the next).

The cylindrical chamber 40 consists of a cylindrical side wall 50 and acircular ceiling 52 integrally formed with the side wall 50 so that theside wall 50 and ceiling 52 constitute a single piece of material, suchas silicon. However, the invention may be carried out with the side wall50 and ceiling 52 formed as separate pieces, as will be described laterin this specification. The circular ceiling 52 may be of any suitablecross-sectional shape such as planar (FIG. 4A), dome (FIG. 4C), conical(FIG. 4D), truncated conical (FIG. 4E), cylindrical or any combinationof such shapes or curve of rotation. Such a combination will bediscussed later in this specification. Generally the vertical pitch ofthe solenoid 42 (i.e., its vertical height divided by its horizontalwidth) exceeds the vertical pitch of the ceiling 52, even for ceilingsdefining 3-dimensional surfaces such as dome, conical, truncated conicaland so forth. The purpose for this, at least in the preferredembodiment, is to concentrate the induction of the antenna near theantenna symmetry axis, as discussed previously in this specification. Asolenoid having a pitch exceeding that of the ceiling is referred toherein as a non-conformal solenoid, meaning that, in general, its shapedoes not conform with the shape of the ceiling, and more specificallythat its vertical pitch exceeds the vertical pitch of the ceiling. A2-dimensional or flat ceiling has a vertical pitch of zero, while a3-dimensional ceiling has a non-zero vertical pitch.

A pedestal 54 at the bottom of the chamber 40 supports a planarworkpiece 56 in a workpiece support plane during processing. Theworkpiece 56 is typically a semiconductor wafer and the workpiecesupport plane is generally the plane of the wafer or workpiece 56. Thechamber 40 is evacuated by a pump (not shown in the drawing) through anannular passage 58 to a pumping annulus 60 surrounding the lower portionof the chamber 40. The interior of the pumping annulus may be lined witha replaceable metal liner 60a. The annular passage 58 is defined by thebottom edge 50a of the cylindrical side wall 50 and a planar ring 62surrounding the pedestal 54. Process gas is furnished into the chamber40 through any one or all of a variety of gas feeds. In order to controlprocess gas flow near the workpiece center, a center gas feed 64a canextend downwardly through the center of the ceiling 52 toward the centerof the workpiece 56 (or the center of the workpiece support plane). Inorder to control gas flow near the workpiece periphery (or near theperiphery of the workpiece support plane), plural radial gas feeds 64b,which can be controlled independently of the center gas feed 64a, extendradially inwardly from the side wall 50 toward the workpiece periphery(or toward the workpiece support plane periphery), or base axial gasfeeds 64c extend upwardly from near the pedestal 54 toward the workpieceperiphery, or ceiling axial gas feeds 64d can extend downwardly from theceiling 52 toward the workpiece periphery. Etch rates at the workpiececenter and periphery can be adjusted independently relative to oneanother to achieve a more radially uniform etch rate distribution acrossthe workpiece by controlling the process gas flow rates toward theworkpiece center and periphery through, respectively, the center gasfeed 64a and any one of the outer gas feeds 64b-d. This feature of theinvention can be carried out with the center gas feed 64a and only oneof the peripheral gas feeds 64b-d.

The solenoidal coil antenna 42 is wound around a housing 66 surroundingthe center gas feed 64. A plasma source RF power supply 68 is connectedacross the coil antenna 42 and a bias RF power supply 70 is connected tothe pedestal 54.

Confinement of the overhead coil antenna 42 to the center region of theceiling 52 leaves a large portion of the top surface of the ceiling 52unoccupied and therefore available for direct contact with temperaturecontrol apparatus including, for example, plural radiant heaters 72 suchas tungsten halogen lamps and a water-cooled cold plate 74 which may beformed of copper or aluminum for example, with coolant passages 74aextending therethrough. Preferably the coolant passages 74a contain acoolant of a known variety having a high thermal conductivity but a lowelectrical conductivity, to avoid electrically loading down the antennaor solenoid 42. The cold plate 74 provides constant cooling of theceiling 52 while the maximum power of the radiant heaters 72 is selectedso as to be able to overwhelm, if necessary, the cooling by the coldplate 74, facilitating responsive and stable temperature control of theceiling 52. The large ceiling area irradiated by the heaters 72 providesgreater uniformity and efficiency of temperature control. (It should benoted that radiant heating is not necessarily required in carrying outthe invention, and the skilled worker may choose to employ an electricheating element instead, as will be described later in thisspecification.) If the ceiling 52 is silicon, as disclosed in co-pendingU.S. application Ser. No. 08/597,577 filed Feb. 2, 1996 by Kenneth S.Collins et al., then there is a significant advantage to be gained bythus increasing the uniformity and efficiency of the temperature controlacross the ceiling. Specifically, where a polymer precursor and etchantprecursor process gas (e.g., a fluorocarbon gas) is employed and whereit is desirable to scavenge the etchant (e.g., fluorine), the rate ofpolymer deposition across the entire ceiling 52 and/or the rate at whichthe ceiling 52 furnishes a fluorine etchant scavenger material (silicon)into the plasma is better controlled by increasing the contact area ofthe ceiling 52 with the temperature control heater 72. The solenoidantenna 42 increases the available contact area on the ceiling 52because the solenoid windings 44 are concentrated at the center axis ofthe ceiling 52.

The increase in available area on the ceiling 52 for thermal contact isexploited in a preferred implementation by a highly thermally conductivetorus 75 (formed of a ceramic such as aluminum nitride, aluminum oxideor silicon nitride or of a non-ceramic like silicon or silicon carbideeither lightly doped or undoped) whose bottom surface rests on theceiling 52 and whose top surface supports the cold plate 74. One featureof the torus 75 is that it displaces the cold plate 74 well-above thetop of the solenoid 42. This feature substantially mitigates or nearlyeliminates the reduction in inductive coupling between the solenoid 42and the plasma which would otherwise result from a close proximity ofthe conductive plane of the cold plate 74 to the solenoid 42. In orderto prevent such a reduction in inductive coupling, it is preferable thatthe distance between the cold plate 74 and the top winding of thesolenoid 42 be at least a substantial fraction (e.g., one half) of thetotal height of the solenoid 42. Plural axial holes 75a extendingthrough the torus 75 are spaced along two concentric circles and holdthe plural radiant heaters or lamps 72 and permit them to directlyirradiate the ceiling 52. For greatest lamp efficiency, the holeinterior surface may be lined with a reflective (e.g., aluminum) layer.The center gas feed 64a of FIG. 4 may be replaced by a radiant heater 72(as shown in FIG. 5), depending upon the particular reactor design andprocess conditions. The ceiling temperature is sensed by a sensor suchas a thermocouple 76 extending through one of the holes 75a not occupiedby a lamp heater 72. For good thermal contact, a highly thermallyconductive elastomer 73 such as silicone rubber impregnated with boronnitride is placed between the ceramic torus 75 and the copper cold plate74 and between the ceramic torus 75 and the silicon ceiling 52.

As disclosed in the above-referenced co-pending application, the chamber40 may be an all-semiconductor chamber, in which case the ceiling 52 andthe side wall 50 are both a semiconductor material such as silicon orsilicon carbide. As described in the above-referenced co-pendingapplication, controlling the temperature of, and RF bias power appliedto, either the ceiling 52 or the wall 50 regulates the extent to whichit furnishes fluorine scavenger precursor material (silicon) into theplasma or, alternatively, the extent to which it is coated with polymer.The material of the ceiling 52 is not limited to silicon but may be, inthe alternative, silicon carbide, silicon dioxide (quartz), siliconnitride, aluminum nitride or a ceramic such as aluminum oxide.

As described in the above-referenced co-pending application, the chamberwall or ceiling 50, 52 need not be used as the source of a fluorinescavenger material. Instead, a disposable semiconductor (e.g., siliconor silicon carbide) member can be placed inside the chamber 40 andmaintained at a sufficiently high temperature to prevent polymercondensation thereon and permit silicon material to be removed therefrominto the plasma as fluorine scavenging material. In this case, the wall50 and ceiling 52 need not necessarily be silicon, or if they aresilicon they may be maintained at a temperature (and/or RF bias) near orbelow the polymer condensation temperature (and/or a polymercondensation RF bias threshold) so that they are coated with polymerfrom the plasma so as to be protected from being consumed. While thedisposable silicon member may take any appropriate form, in theembodiment of FIG. 4 the disposable silicon member is an annular ring 62surrounding the pedestal 54. Preferably, the annular ring 62 is highpurity silicon and may be doped to alter its electrical or opticalproperties. In order to maintain the silicon ring 62 at a sufficienttemperature to ensure its favorable participation in the plasma process(e.g., its contribution of silicon material into the plasma for fluorinescavenging), plural radiant (e.g., tungsten halogen lamp) heaters 77arranged in a circle under the annular ring 62 heat the silicon ring 62through a quartz window 78. As described in the above-referencedco-pending application, the heaters 77 are controlled in accordance withthe measured temperature of the silicon ring 62 sensed by a temperaturesensor 79 which may be a remote sensor such as an optical pyrometer or afluoro-optical probe. The sensor 79 may extend partially into a verydeep hole 62a in the ring 62, the deepness and narrowness of the holetending at least partially to mask temperature-dependent variations inthermal emissivity of the silicon ring 62, so that it behaves more likea gray-body radiator for more reliable temperature measurement.

As described in U.S. application Ser. No. 08/597,577 referred to above,an advantage of an all-semiconductor chamber is that the plasma is freeof contact with contaminant producing materials such as metal, forexample. For this purpose, plasma confinement magnets 80, 82 adjacentthe annular opening 58 prevent or reduce plasma flow into the pumpingannulus 60. To the extent any polymer precursor and/or active speciessucceeds in entering the pumping annulus 60, any resulting polymer orcontaminant deposits on the replaceable interior liner 60a may beprevented from re-entering the plasma chamber 40 by maintaining theliner 60a at a temperature significantly below the polymer condensationtemperature, for example, as disclosed in the referenced co-pendingapplication.

A wafer slit valve 84 through the exterior wall of the pumping annulus60 accommodates wafer ingress and egress. The annular opening 58 betweenthe chamber 40 and pumping annulus 60 is larger adjacent the wafer slitvalve 84 and smallest on the opposite side by virtue of a slant of thebottom edge of the cylindrical side wall 50 so as to make the chamberpressure distribution more symmetrical with a non-symmetrical pump portlocation.

Maximum mutual inductance near the chamber center axis 46 is achieved bythe vertically stacked solenoidal windings 44. In the embodiment of FIG.4, another winding 45 outside of the vertical stack of windings 44 butin the horizontal plane of the bottom solenoidal winding 44a may beadded, provided the additional winding 45 is close to the bottomsolenoidal winding 44a.

Referring specifically now to the preferred dual solenoid embodiment ofFIG. 5, a second outer vertical stack or solenoid 120 of windings 122 atan outer location (i.e, against the outer circumferential surface of thethermally conductive torus 75) is displaced by a radial distance 6R fromthe inner vertical stack of solenoidal windings 44. Note that in FIG. 5confinement of the inner solenoidal antenna 42 to the center and theouter solenoidal antenna 120 to the periphery leaves a large portion ofthe top surface of the ceiling 52 available for direct contact with thetemperature control apparatus 72, 74, 75, as in FIG. 4A. An advantage isthat the larger surface area contact between the ceiling 52 and thetemperature control apparatus provides a more efficient and more uniformtemperature control of the ceiling 52.

For a reactor in which the side wall and ceiling are formed of a singlepiece of silicon for example with an inside diameter of 12.6 in (32 cm),the wafer-to-ceiling gap is 3 in (7.5 cm), and the mean diameter of theinner solenoid was 3.75 in (9.3 cm) while the mean diameter of the outersolenoid was 11.75 in (29.3 cm) using 3/16 in diameter hollow coppertubing covered with a 0.03 thick teflon insulation layer, each solenoidconsisting of four turns and being 1 in (2.54 cm) high. The outer stackor solenoid 120 is energized by a second independently controllableplasma source RF power supply 96. The purpose is to permit differentuser-selectable plasma source power levels to be applied at differentradial locations relative to the workpiece or wafer 56 to permitcompensation for known processing non-uniformities across the wafersurface, a significant advantage. In combination with the independentlycontrollable center gas feed 64a and peripheral gas feeds 64b-d, etchperformance at the workpiece center may be adjusted relative to etchperformance at the edge by adjusting the RF power applied to the innersolenoid 42 relative to that applied to the outer solenoid 90 andadjusting the gas flow rate through the center gas feed 64a relative tothe flow rate through the outer gas feeds 64b-d. While the plasmareactor solves or at least ameliorates the problem of a center null ordip in the inductance field as described above, there may be otherplasma processing non-uniformity problems, and these can be compensatedin the versatile embodiment of FIG. 5 by adjusting the relative RF powerlevels applied to the inner and outer antennas. For effecting thispurpose with greater convenience, the respective RF power supplies 68,96 for the inner and outer solenoids 42, 90 may be replaced by a commonpower supply 97a and a power splitter 97b which permits the user tochange the relative apportionment of power between the inner and outersolenoids 42, 90 while preserving a fixed phase relationship between thefields of the inner and outer solenoids 42, 90. This is particularlyimportant where the two solenoids 42, 90 receive RF power at the samefrequency. Otherwise, if the two independent power supplies 68, 96 areemployed, then they may be powered at different RF frequencies, in whichcase it is preferable to install RF filters at the output of each RFpower supply 68, 96 to avoid off-frequency feedback from couplingbetween the two solenoids. In this case, the frequency difference shouldbe sufficient to time-average out coupling between the two solenoidsand, furthermore, should exceed the rejection bandwidth of the RFfilters. A preferred mode is to make each frequency independentlyresonantly matched to the respective solenoid, and each frequency may bevaried to follow changes in the plasma impedance (thereby maintainingresonance) in lieu of conventional impedance matching techniques. Inother words, the RF frequency applied to the antenna is made to followthe resonant frequency of the antenna as loaded by the impedance of theplasma in the chamber. In such implementations, the frequency ranges ofthe two solenoids should be mutually exclusive. In an alternative mode,the two solenoids are driven at the same RF frequency and in this caseit is preferable that the phase relationship between the two be such asto cause constructive interaction or superposition of the fields of thetwo solenoids. Generally, this requirement will be met by a zero phaseangle between the signals applied to the two solenoids if they are bothwound in the same sense. Otherwise, if they are oppositely wound, thephase angle is preferably 180°. In any case, coupling between the innerand outer solenoids can be minimized or eliminated by having arelatively large space between the inner and outer solenoids 42, 90, aswill be discussed below in this specification.

The range attainable by such adjustments is increased by increasing theradius of the outer solenoid 90 to increase the spacing between theinner and outer solenoids 42, 90, so that the effects of the twosolenoids 42, 90 are more confined to the workpiece center and edge,respectively. This permits a greater range of control in superimposingthe effects of the two solenoids 42, 90. For example, the radius of theinner solenoid 42 should be no greater than about half the workpieceradius and preferably no more than about a third thereof. (The minimumradius of the inner solenoid 42 is affected in part by the diameter ofthe conductor forming the solenoid 42 and in part by the need to providea finite non-zero circumference for an arcuate--e.g., circular--currentpath to produce inductance.) The radius of the outer coil 90 should beat least equal to the workpiece radius and preferably 1.5 or more timesthe workpiece radius. With such a configuration, the respective centerand edge effects of the inner and outer solenoids 42, 90 are sopronounced that by increasing power to the inner solenoid the chamberpressure can be raised into the hundreds of mT while providing a uniformplasma, and by increasing power to the outer solenoid 90 the chamberpressure can be reduced to on the order of 0.01 mT while providing auniform plasma. Another advantage of such a large radius of the outersolenoid 90 is that it minimizes coupling between the inner and outersolenoids 42, 90.

FIG. 5 indicates in dashed line that a third solenoid may be added as anoption, which is desirable for a very large chamber diameter.

FIG. 6 illustrates a variation of the embodiment of FIG. 5 in which theouter solenoid 90 is replaced by a planar winding 100.

FIG. 7A illustrates a variation of the embodiment of FIG. 4 in which thecenter solenoidal winding includes not only the vertical stack 42 ofwindings 44 but in addition a second vertical stack 102 of windings 104closely adjacent to the first stack 42 so that the two stacks constitutea double-wound solenoid 106. Referring to FIG. 7B, the doubly woundsolenoid 106 may consist of two independently wound single solenoids 42,102, the inner solenoid 42 consisting of the windings 44a, 44b, and soforth and the outer solenoid 102 consisting of the winding 104a, 104band so forth. Alternatively, referring to FIG. 7C, the doubly woundsolenoid 106 may consist of vertically stacked pairs of at least nearlyco-planar windings. In the alternative of FIG. 7C, each pair of nearlyco-planar windings (e.g., the pair 44a, 104a or the pair 44b, 104b) maybe formed by helically winding a single conductor. The term "doublywound" used herein refers to winding of the type shown in either FIG. 7Bor 7C. In addition, the solenoid winding may not be merely doubly woundbut may be triply wound or more and in general it can consists of pluralwindings at each plane along the axis of symmetry. Such multiple-woundsolenoids may be employed in either one or both the inner and outersolenoids 42, 90 of the dual-solenoid embodiment of FIG. 5.

FIG. 8 illustrates a variation of the embodiment of FIG. 7A in which anouter doubly wound solenoid 1 10 concentric with the inner doubly woundsolenoid 106 is placed at a radial distance 8R from the inner solenoid106.

FIG. 9 illustrates a variation of the embodiment of FIG. 8 in which theouter doubly wound solenoid 110 is replaced by an ordinary outersolenoid 112 corresponding to the outer solenoid employed in theembodiment of FIG. 5.

FIG. 10 illustrates another preferred embodiment in which the solenoid42 of FIG. 5 is placed at a location displaced by a radial distance orfrom the center gas feed housing 66. In the embodiment of FIG. 4, δr iszero while in the embodiment of FIG. 10 δr is a significant fraction ofthe radius of the cylindrical side wall 50. Increasing δr to the extentillustrated in FIG. 10 may be helpful as an alternative to theembodiments of FIGS. 4, 5, 7 and 8 for compensating for non-uniformitiesin addition to the usual center dip in plasma ion density described withreference to FIGS. 3D and 3E. Similarly, the embodiment of FIG. 10 maybe helpful where placing the solenoid 42 at the minimum distance fromthe chamber center axis 46 (as in FIG. 4) would so increase the plasmaion density near the center of the wafer 56 as to over-correct for theusual dip in plasma ion density near the center and create yet anothernon-uniformity in the plasma process behavior. In such a case, theembodiment of FIG. 10 is preferred where δr is selected to be an optimumvalue which provides the greatest uniformity in plasma ion density.Ideally in this case, δr is selected to avoid both under-correction andover-correction for the usual center dip in plasma ion density. Thedetermination of the optimum value for δr can be carried out by theskilled worker by trial and error steps of placing the solenoid 42 atdifferent radial locations and employing conventional techniques todetermine the radial profile of the plasma ion density at each step.

FIG. 11 illustrates an embodiment in which the solenoid 42 has aninverted conical shape while FIG. 12 illustrates an embodiment in whichthe solenoid 42 has an upright conical shape.

FIG. 13 illustrates an embodiment in which the solenoid 42 is combinedwith a planar helical winding 120. The planar helical winding has theeffect of reducing the severity with which the solenoid winding 42concentrates the induction field near the center of the workpiece bydistributing some of the RF power somewhat away from the center. Thisfeature may be useful in cases where it is necessary to avoidover-correcting for the usual center null. The extent of such diversionof the induction field away from the center corresponds to the radius ofthe planar helical winding 120. FIG. 14 illustrates a variation of theembodiment of FIG. 13 in which the solenoid 42 has an inverted conicalshape as in FIG. 11. FIG. 15 illustrates another variation of theembodiment of FIG. 13 in which the solenoid 42 has an upright conicalshape as in the embodiment of FIG. 12.

The RF potential on the ceiling 52 may be increased, for example toprevent polymer deposition thereon, by reducing its effective capacitiveelectrode area relative to other electrodes of the chamber (e.g., theworkpiece and the sidewalls). FIG. 16 illustrates how this can beaccomplished by supporting a smaller-area version of the ceiling 52' onan outer annulus 200, from which the smaller-area ceiling 52' isinsulated. The annulus 200 may be formed of the same material (e.g.,silicon) as the ceiling 52' and may be of a truncated conical shape(indicated in solid line) or a truncated dome shape (indicated in dashedline). A separate RF power supply 205 may be connected to the annulus200 to permit more workpiece center versus edge process adjustments.

FIG. 17A illustrates a variation of the embodiment of FIG. 5 in whichthe ceiling 52 and side wall 50 are separate semiconductor (e.g.,silicon) pieces insulated from one another having separately controlledRF bias power levels applied to them from respective RF sources 210, 212to enhance control over the center etch rate and selectivity relative tothe edge. As set forth in greater detail in above-referenced U.S.application Ser. No. 08/597,577 filed Feb. 2, 1996 by Kenneth S. Collinset al., the ceiling 52 may be a semiconductor (e.g., silicon) materialdoped so that it will act as an electrode capacitively coupling the RFbias power applied to it into the chamber and simultaneously as a windowthrough which RF power applied to the solenoid 42 may be inductivelycoupled into the chamber. The advantage of such a window-electrode isthat an RF potential may be established directly over the wafer (e.g.,for controlling ion energy) while at the same time inductively couplingRF power directly over the wafer. This latter feature, in combinationwith the separately controlled inner and outer solenoids 42, 90 andcenter and peripheral gas feeds 64a, 64b greatly enhances the ability toadjust various plasma process parameters such as ion density, ionenergy, etch rate and etch selectivity at the workpiece center relativeto the workpiece edge to achieve an optimum uniformity. In thiscombination, gas flow through individual gas feeds is individually andseparately controlled to achieve such optimum uniformity of plasmaprocess parameters.

FIG. 17A illustrates how the lamp heaters 72 may be replaced by electricheating elements 72'. As in the embodiment of FIG. 4, the disposablesilicon member is an annular ring 62 surrounding the pedestal 54.Preferably, the annular ring 62 is high purity silicon and may be dopedto alter its electrical or optical properties. In order to maintain thesilicon ring 62 at a sufficient temperature to ensure its favorableparticipation in the plasma process (e.g., its contribution of siliconmaterial into the plasma for fluorine scavenging), plural radiant (e.g.,tungsten halogen lamp) heaters 77 arranged in a circle under the annularring 62 heat the silicon ring 62 through a quartz window 78. Asdescribed in the above-referenced co-pending application, the heaters 77are controlled in accordance with the measured temperature of thesilicon ring 62 sensed by a temperature sensor 79 which may be a remotesensor such as an optical pyrometer or a fluoro-optical probe. Thesensor 79 may extend partially into a very deep hole 62a in the ring 62,the deepness and narrowness of the hole tending at least partially tomask temperature-dependent variations in thermal emissivity of thesilicon ring 62, so that it behaves more like a gray-body radiator formore reliable temperature measurement.

FIG. 17B illustrates another variation in which the ceiling 52 itselfmay be divided into an inner disk 52a and an outer annulus 52belectrically insulated from one another and separately biased byindependent RF power sources 214, 216 which may be separate outputs of asingle differentially controlled RF power source.

In accordance with an alternative embodiment, a user-accessible centralcontroller 300 shown in FIGS. 17A and 17B, such as a programmableelectronic controller including, for example, a conventionalmicroprocessor and memory, is connected to simultaneously control gasflow rates through the central and peripheral gas feeds 64a, 64, RFplasma source power levels applied to the inner and outer antennas 42,90 and RF bias power levels applied to the ceiling 52 and side wall 50respectively (in FIG. 17A) and the RF bias power levels applied to theinner and outer ceiling portions 52a, 52b (in FIG. 17B), temperature ofthe ceiling 52 and the temperature of the silicon ring 62. A ceilingtemperature controller 218 governs the power applied by a lamp powersource 220 to the heater lamps 72' by comparing the temperature measuredby the ceiling temperature sensor 76 with a desired temperature known tothe controller 300. A ring temperature controller 222 controls the powerapplied by a heater power source 224 to the heater lamps 77 facing thesilicon ring 62 by comparing the ring temperature measured by the ringsensor 79 with a desired ring temperature stored known to the controller222. The master controller 300 governs the desired temperatures of thetemperature controllers 218 and 222, the RF power levels of the solenoidpower sources 68, 96, the RF power levels of the bias power sources 210,212 (FIG. 17A) or 214, 216 (FIG. 17B), the wafer bias level applied bythe RF power source 70 and the gas flow rates supplied by the variousgas supplies (or separate valves) to the gas inlets 64a-d. The key tocontrolling the wafer bias level is the RF potential difference betweenthe wafer pedestal 54 and the ceiling 52. Thus, either the pedestal RFpower source 70 or the ceiling RF power source 212 may be simply a shortto RF ground. With such a programmable integrated controller, the usercan easily optimize apportionment of RF source power, RF bias power andgas flow rate between the workpiece center and periphery to achieve thegreatest center-to-edge process uniformity across the surface of theworkpiece (e.g., uniform radial distribution of etch rate and etchselectivity). Also, by adjusting (through the controller 300) the RFpower applied to the solenoids 42, 90 relative to the RF powerdifference between the pedestal 54 and ceiling 52, the user can operatethe reactor in a predominantly inductively coupled mode or in apredominantly capacitively coupled mode.

While the various power sources connected in FIG. 17A to the solenoids42, 90, the ceiling 52, side wall 50 (or the inner and outer ceilingportions 52a, 52b as in FIG. 17B) have been described as operating at RFfrequencies, the invention is not restricted to any particular range offrequencies, and frequencies other than RF may be selected by theskilled worker in carrying out the invention.

In a preferred embodiment of the invention, the high thermalconductivity spacer 75, the ceiling 52 and the side wall 50 areintegrally formed together from a single piece of crystalline silicon.

Referring again to FIG. 5, a preferred plasma processing chamberincludes a window/electrode 52. The window/electrode 52 is fabricatedfrom semiconducting material as described in detail in theabove-referenced applications so that it may function as both a windowto RF electromagnetic or inductive power coupling from one or moreexternal (outside chamber) antennas or coils to the plasma within thechamber and as an electrode for electrostatically or capacitivelycoupling RF power to the plasma within the chamber (or for terminatingor providing a ground or return path for such capacitive orelectrostatic coupling of RF power) or for biasing the workpiece orwafer.

The window/electrode 52 may be any shape as described in theabove-referenced applications, but in this example is approximately aflat disc which may optionally include a cylindrical wall or skirtextending outward from the disk, such as for plasma confinement asdescribed in the above-referenced applications.

The window/electrode 52 is interfaced to the heat sink 74 through theheat transfer material 75. Typically the heat sink 74 is a water cooledmetal plate, preferably a good thermal conductor such as aluminum orcopper, but may optionally be a non-metal. The heat sink 74 typically acooling apparatus preferably of the type which uses a liquid coolantsuch as water or ethylene-glycol that is forced through cooling passagesof sufficient surface area within the heat sink 74 by a closed-loop heatexchanger or chiller. The liquid flow rate or temperature may bemaintained approximately constant. Alternatively, the liquid flow rateor temperature may be an output variable of the temperature controlsystem.

Preferably, radiant heating is used to apply heat to thewindow/electrode. The radiant heaters 72 are a plurality of tungstenfilament lamps utilizing a quartz envelope filled with a mixture ofhalogen and inert gases. Radiant heaters are preferred to other heatertypes because thermal lag is minimized: The thermal capacitance of atungsten filament lamp is very low, such that the time response offilament temperature (and thus of power output) to a change in powersetting is short (<1 second), and since the heat transfer mechanismbetween lamp filament and load is by radiation, the total thermal lagfor heating is minimized. In addition, since the heat transfer mechanismbetween lamp filament and load is by radiation, the total thermal lagfor heating is minimized. In addition, since the thermal capacitance ofa tungsten filament lamp is very low, the amount of stored thermalenergy in the lamp is very low, and when a reduction in heating power iscalled for by the control system, the filament temperature may bequickly dropped and the lamp output power thus also quickly drops. Asshown in FIG. 5, the lamps 72 directly radiate the load (thewindow/electrode 52) for the fastest possible response. However,alternatively, the lamps 72 may radiate the heat transfer material 75.

Lamp heating may be provided in more than one zone, i.e. lamps at two ormore radii from the axis of the window/electrode to improve thermaluniformity of window/electrode. For maximum thermal uniformity, lamps inthe two or more zones may be provided with separate control, each zoneutilizing its own temperature measurement, control system, and outputtransducer. This is especially useful when the heat flux spatialdistribution from inside the chamber varies depending on processparameters, processes, process sequences, or other boundary conditions.

The heat transfer material 75 may be formed integrally with thewindow/electrode 52 that is formed of the same material into a singlepiece structure for elimination of a thermal contact resistance thatwould be present if heat transfer material 75 and window/electrode 52were two separate parts. Alternatively, the heat transfer material 75and the window/electrode 52 may be two parts of same or differentmaterials that are bonded together, (preferably with a high electricalresistivity material since the window/electrode 52 is used for inductiveor electromagnetic coupling of RF or microwave power using inductiveantennas 90, 92 and/or 42, 44), minimizing the thermal contactresistance between the heat transfer material 75 and thewindow/electrode 52.

Alternatively, the heat transfer material 75 and the window/electrode 52may be two parts of same or different materials that are interfacedtogether through a contact resistance. In this case, the heat transfermaterial 75 is preferably made of a highly thermally conductive materialof high electrical resistivity. Additionally, a low product of densityand specific heat are preferred. SiC, Si, AIN, and AI₂ O₃ are examples.

    ______________________________________                                        Properties of SiC are indicated below:                                        ______________________________________                                        Thermal conductivity:                                                                           130 watt/meter*Kelvin                                       Electrical resistivity:                                                                         >10.sup.5 ohm*cm                                            Specific Heat:    0.66 joule/gram*Kelvin                                      Density:          3.2 gram/cm.sup.3                                           ______________________________________                                    

Silicon may also be used, if lightly (not heavily) doped (i.e. 10¹⁴/cm³) and has the following properties:

    ______________________________________                                        Thermal conductivity:                                                                            80 watt/meter*Kelvin                                       Electrical resistivity:                                                                          20-100 ohm*cm                                              Specific Heat:     0.7 joule/gram*Kelvin                                      Density:           2.3 gram/cm.sup.3                                          ______________________________________                                    

Aluminum nitride or aluminum oxide are other alternatives.

The heat transfer material 75 may be bonded to the heat sink 74 bytechniques well known in the art (e.g., using bonding materials such asthermoplastics, epoxies, or other organic or inorganic bondingmaterials), without the restriction of requiring high electricalresistivity bonding material in the area proximate the heat sink 74.This provides a very low thermal contact resistance between heattransfer material 75 and heat sink 74.

The heat transfer material 75 also serves to separate the inductiveantennas 90, 92 and/or 42, 44 from the heat sink 74 which if it ismetal, forms a ground plane or reflector to the induction fieldgenerated in the vicinity of each inductive antenna 90, 92 and/or 42,44. If the heat sink 74 is metal and is too close to the inductiveantenna 90, 92 and/or 42, 44, then eddy currents are induced in theground plane, causing power loss. In addition, the RF currents throughthe antenna 90, 92 and/or 42, 44 become very large to drive a given RFpower, increasing I² R losses in the circuit. The antennas 90, 92 and/or42, 44 are each four turns comprised of 3/16" diameter water cooledcopper tubing insulated with 1/4" outside diameter teflon tubingyielding coils 1" in height. An acceptable distance between thewindow/electrode 52 and the metal heat sink 74 is about 2", yieldingabout a 1" distance between the top of the antenna 90, 92 and/or 42, 44and the heat sink 74.

As described above, thermal contact resistances between the heattransfer material 75 and the window, electrode 52, and between the heattransfer material 75 and the heat sink 74 can be minimized by bondingthe materials together. Also described above was an example of formingthe window/electrode 52 and the heat transfer material 75 from a singlepiece of material, eliminating one thermal contact resistance. However,in some cases, one or both thermal contact resistances cannot beavoided. However, the thermal contact resistance(s) can be minimized inaccordance with a feature of the plasma reactor, which will now beintroduced.

Thermal contact resistance between two parts is comprised of twoparallel elements: 1) mechanical point contact between the parts, and 2)conduction through air (or other medium) between the parts. In theabsence of air or other medium, the thermal contact resistance betweenthe two parts is very high and typically unacceptable for heating and/orcooling of the window/electrode 52 due to the high heat loads imposed onit during typical plasma reactor operation. The presence of air yields alower thermal contact resistance than mechanical point contact alone,but is typically marginal depending on the effective gap between parts,which is a function of the surface roughness and flatness of both parts.For air in the high pressure continuum regime wherein the mean-free-pathin the gas is small relative to the effective gap between parts, thethermal conductivity of the air is invariant with gas pressure, and thethermal conductance per unit area is simply the ratio of the thermalconductivity of air to the effective gap. For air at atmosphericpressure and 100 degrees C, the thermal conductivity is about 0.03watt/meter*Kelvin. Heat transfer across the gap is limited by the lowchamber pressure and by the fact that the mechanical contact between thetwo parts is only point contact.

In order to improve heat transfer, a thermally conductive gas such as(preferably) helium or another one of the inert gases such as argon,xenon and so forth, can be placed in the gap between the between theheat transfer material 75 and the heat sink 74 and/or in the gap betweenthe heat transfer material 75 and the window/electrode 52, in accordancewith a first embodiment of the plasma reactor. The thermally conductivegas in the gap is best pressurized above the chamber pressure to as highas atmospheric pressure, although preferably the pressure of the thermaltransfer gas in the gap is between the chamber pressure and atmosphericpressure. Helium is a preferred choice for the thermally conductive gasbecause helium has a thermal conductivity of about 0.18watt/meter*Kelvin at atmospheric pressure and 100 degree C. To minimizethermal contact resistance between the heat transfer material 75 and theheat sink 74, helium can be provided to each interface therebetweenthrough a helium distribution manifold within the heat sink 74, as willbe described in detail below in this specification. As will also bedescribed below in detail, an O-ring of small cross-section and lowdurometer can be used to reduce helium leakage and between heat transfermaterial 75 and heat sink 74. Through-holes from the top surface of theheat transfer material or rings 75 can connect a helium passage from anupper interface between the heat sink 74 and the heat transfer materialring 75, to interface between the heat transfer material ring 75 and thewindow/electrode 52. Each heat transfer ring 75 may be formed of anygood thermal conductor which does not tend to absorb an RF field (e.g.,a thermal conductor with relatively high electrical resistivity). Onesuitable material is silicon carbide, although other materials may beemployed which may be semiconductive or dielectric, such as ceramicmaterials of the type including silicon nitride, aluminum nitride oraluminum oxide. However, silicon carbide is preferred as the materialfor the heat transfer rings 75.

Helium can be supplied to the aforementioned helium distributionmanifold located within heat sink 74 at a pressure somewhat aboveatmospheric to minimize dilution of helium by air which could otherwiseincrease the thermal contact resistance.

Other materials may be used in between the heat transfer material 75 andthe window/electrode 52, and between the heat transfer material 75 andthe heat sink 74 to minimize thermal contact resistances. Examples arethermally conductive, compliant elastomeric pads such as boron nitrideor silicon carbide or silicon or aluminum nitride or aluminum oxide, andsimilar materials. Metal-impregnated elastomeric pads may be used at theinterface adjacent the heat sink 74, but not adjacent thewindow/electrode 52 for the same reasons explained above that in generala conductor may not be placed adjacent the window electrode 52. Softmetals such as 1100 series aluminum, indium, copper or nickel may beused at the interface adjacent the heat sink 74, but not adjacent thewindow/electrode 52 for the reasons explained above.

The cooling capability and heating power requirements are best selectedor sized depending on 1) temperature control range required of thewindow/electrode, 2) the minimum and maximum heat internal loads, 3) thematerial properties and physical dimensions of the window/electrode, theheat transfer materials, the heat sink plate and the interfaces betweenheat sink plate, heat transfer materials, and window/electrode, and 4)the temperature of the heat sink. Generally, the cooling capability issized first for the lowest required temperature of operation of thewindow/electrode with the highest internal heat load, and the heatingpower is then sized to overwhelm the cooling for the highest requiredtemperature of operation of the window/electrode with the lowestinternal heat load (typically zero internal heat load).

FIG. 18 corresponds to an enlarged view of a portion of FIG. 5 andillustrates one implementation of the foregoing concept of a thermallyconductive gas interface at both faces (top and bottom) of the thermallyconductive spacer 75 which is not integrally formed with thesemiconductor window electrode 52. In FIG. 18, the overlying cold plate74 sandwiches plural cylindrical spacer rings 75 with the underlyingsemiconductor window electrode 52 as illustrated in FIG. 5. Each spaceror torus 75 can be a material different from the semiconductor windowelectrode 52, as discussed above. A manifold 1000 is formed in the coldplate 74 into which a thermally conductive gas such as helium may besupplied from a source 1010 under positive pressure. Preferably, but notnecessarily, the positive pressure of the source 1010 is selected so asto maintain the pressure within the thin gap between the two partssignificantly above the reactor chamber pressure but below atmosphericpressure. Gas orifices 1020 connect the manifold 1000 to the topinterface 1030 between the cold plate 74 and the spacer 75, permittingthe thermally conductive gas (e.g., Helium) to fill the voids in theinterface 1030. An axial passage 1040 is provided through the spacer 75between its top and bottom faces. The axial passage 1040 connects thetop interface 1030 with a bottom interface 1050 between the bottom faceof the spacer 75 and the underlying semiconductor window electrode 52.The axial passage 1040 permits the thermally conductive gas to flow fromthe top interface 1030 to the bottom interface 1050 to fill voids in thebottom interface 1050, so that the thermally conductive gas fills voidsin both the top and bottom interfaces 1030, 1050. By the source 1010maintaining the thermally conductive gas manifold 1000 under positivepressure (e.g., 5 psi higher than the chamber pressure), the gas flowsto both interfaces 1030, 1050. In order to reduce or prevent leaking ofthe thermally conductive gas from the interfaces 1030, 1050, smallcross-section O-rings 1070, 1080 are sandwiched in the top and bottominterfaces, respectively, at the time of assembly. The O-rings 1070,1080 define nearly infinitesimally thin gas-containing volumes in therespective interfaces 1030, 1050 in communication with the respectivegas manifold 1000, 1040.

FIG. 19 illustrates how the embodiment of FIG. 18 is modified toaccommodate an array of conductive torus spacers 75 integrally formedwith the semiconductor window electrode 52. In this case, the onlyinterface to be filled by the thermally conductive gas is the topinterface 1030.

FIG. 20 corresponds to an enlarged view of a portion of FIG. 5 andillustrates one implementation of the foregoing concept of a thermallyconductive solid interface material at both faces (top and bottom) ofthe thermally conductive spacer 75 which is not integrally formed withthe semiconductor window electrode 52. In FIG. 18, the overlying coldplate 74 sandwiches plural cylindrical spacer rings 75 with theunderlying semiconductor window electrode 52 as illustrated in FIG. 5.Each spacer or torus 75 can be a material different from thesemiconductor window electrode 52, as discussed above. A thermallyconductive solid interface material layer 1085, 1090 is placed in eitheror both the top and bottom interfaces 1030, 1050, respectively. If asolid material layer is placed in only one of the top and bottominterfaces 1030, 1050, then the remaining interface may be filled with athermally conductive gas in the manner of FIG. 18. However, FIG. 20illustrates the case in which a thermally conductive solid interfacematerial layer is in both interfaces 1030, 1050. As discussed above, thesolid interface material layer 1085 in the top interface 1030 may be asoft metal, but the solid interface material layer 1090 in the bottominterface 1050 cannot be highly electrically conductive because it isnext to the electrode 52. The top layer 1085 may be soft aluminum,indium, copper or nickel or an elastomer impregnated with powders orparticles of such metals. Either one of the top and bottom layers 1085,1090 may be an elastomer impregnated with powder or particles of athermally conductive electrically insulating material such as boronnitride, high electrical resistivity (e.g., bulk) silicon carbide orsilicon, aluminum nitride, aluminum oxide and like materials.Alternatively, either one or both of the material layers 1085, 1090 maybe a bonding material, such as thermoplastic, epoxy or an organic orinorganic bonding material.

FIG. 21 illustrates how the embodiment of FIG. 20 is modified toaccommodate an array of conductive torus spacers 75 integrally formedwith the semiconductor window electrode 52. In this case, the onlyinterface to be filled is the top interface 1030.

The invention also solves a severe cooling problem with heated partsinside the reactor chamber which are difficult to cool, such as theheated disposable ring 62 of polymer-hardening precursor materialdescribed above with reference to FIG. 5. (The ring 62 may be heatedonly by plasma heating if no heater is provided, and still requirecooling.) It also solves a problem of heating parts inside the reactorchamber which are difficult to heat directly.

Referring to FIGS. 22 and 23, a cold plate 1100 directly beneath thering 62 and in thermal contact has internal coolant jackets 1110 whichreceive coolant from a coolant circulation pump 1120. The interface 1130between the cold plate 1110 and the ring 62 is filled with a thermalconductivity enhancing substance such as a thermally conductive gas (asin FIG. 22) or a thermally conductive solid material layer 1140 (as inFIG. 23). The thermally conductive gas may be any gas capable ofconducting heat, such as an inert gas or even a gas similar to theprocess gas employed in the reactor chamber, although an inert gas suchas helium is preferred. In the case of the embodiment of FIG. 22employing the thermally conductive gas, a manifold 1150 through the coldplate 1100 is connected to a thermally conductive gas source 1160 whichsupplies thermally conductive gas through the manifold 1160 into theinterface 1130. Leakage of the gas from the interface 1130 is preferablycontrolled to reduce or prevent loss by sandwiching an elastomericlow-cross-section O-ring 1070' between the cold plate 1100 and siliconring 62 at the time the ring is put into its place.

While helium is preferred as the thermally conductive gas in the gap, inthe case of application to heated or cooled parts inside thesub-atmospheric reactor chamber, any gas, including a processing gas,could suffice at a pressure greater than the chamber pressure but belowatmospheric. In such a case, the gas may be allowed to leak into thechamber so that the use of a peripheral seal such as an O-ring orelastomer may not be necessary. Since the thermally conductive gas (or"thermal transfer gas") is pressurized above the chamber pressure, someclamping force must be applied. Such a clamping force can be mechanicalor may be electrostatically induced between the plate 1100 and the ring62. Such an electrostatic clamping feature would require a materialwhich is at least partially electrically insulating to be placed betweenthe plate 1100 and the ring 62. Such a feature can eliminate the needfor a peripheral seal to control leakage of the thermally conductivegas. Such an electrostatic clamping feature is described below in thisspecification with reference to FIG. 26.

The thermally conductive gas can be derived from any suitable source.For example, if the wafer pedestal employs helium cooling underneath thewafer, then a common helium source may be employed for cooling the waferas well as other items (such as the ring 62) inside the chamber.

In the embodiment of FIG. 23, the layer of solid thermally conductivematerial 1140 may be soft aluminum, indium, copper or nickel or anelastomer impregnated with powders or particles of such metals or it maybe an elastomer impregnated with powder or particles of a thermallyconductive electrically insulating material such as boron nitride, highresistivity (e.g., bulk) silicon carbide or silicon, aluminum nitride,aluminum oxide and like materials.

The plasma reactor also concerns cooling chamber walls and chamberliners in a similar manner. Referring to FIG. 24, the chamber side wall50 in any of the reactors discussed above may be cooled by an exteriorcold plate 1210 adjacent a portion of the exterior of the wall 50. Thecold plate includes internal coolant jackets 1220 through which coolantis recirculated by a coolant pump 1230. The interface 1240 between thecold plate 1210 and the side wall 50 is filled with a thermallyconductive gas (such as helium) fed through a manifold 1245 through thecold plate 1210 into the interface 1240 from a gas source 1250 whichmaintains the gas at a positive pressure. Leakage of the thermallyconductive gas from the interface 1240 is reduced or prevented by anO-ring 1260 sandwiched between the cold plate 1210 and the side wall 50at the time of assembly. The O-ring 1260 defines a gas-containing volumeof the interface 1240 which is nearly infinitesimally thin and incommunication with the manifold 1245.

An interior chamber liner 1300 may be cooled by heat conduction to acooled body, such as the side wall 50. In accordance with the plasmareactor, such cooling is enhanced by filling the interface 1310 betweenthe liner 1300 and the interior surface of the side wall 50 with athermally conductive gas such as helium. For this purpose, a radialnarrow gas channel 1320 is provided through the side wall 50 to providegas flow between the interface 1240 on the external side wall surfaceand the interface 1310 on the internal side wall surface. The thermallyconductive gas supplied through the manifold 1245 fills the externalsurface interface 1240 and, through the channel 1320, fills the internalsurface interface 1310 between the liner 1300 and the side wall 50. Toprevent or reduce gas leakage, an O-ring 1370 is sandwiched between theside wall 50 and the liner 1300 at the time of assembly. The O-ring 1370defines a nearly infinitesimally thin gas-containing volume within theinterface 1310 in communication with the gas channel 1245 in the sidewall 50.

FIG. 25 illustrates how the embodiment of FIG. 24 is modified bysubstituting a solid material layer 1370, 1380 in each of the interfaces1240 and 1310, respectively, instead of the thermally conductive gas. Inthe embodiment of FIG. 25, each layer 1370, 1380 of solid thermallyconductive material may be soft aluminum, indium, copper or nickel or anelastomer impregnated with powders or particles of such metals or it maybe an elastomer impregnated with powder or particles of a thermallyconductive electrically insulating material such as boron nitride, highresistivity (e.g., bulk) silicon carbide or silicon, aluminum nitride,aluminum oxide and like materials.

FIG. 26 illustrates how the embodiment of FIG. 22 may be modified toinclude the feature of electrostatic clamping of the ring 62 to the coldplate 1100. In FIG. 26, a dielectric layer 1410 is inserted between thepolymer-hardening precursor ring 62 and the cold plate 1100, and anelectrostatic clamping voltage is applied to the cold plate 1100 from aD.C. voltage source 1420 through a clamping switch 1430. Introduction ofthe insulating or dielectric layer 1410 creates a gap 1130a between thecold plate 1100 and the insulating layer 1410 and a gap 1130b betweenthe ring 62 and the insulating layer 1410. The insulating layer 1410 haspassageways 1412 therethrough so that gas supplied from the passageway1150 into the gap 1130a can flow into the other gap 1130b. While FIG. 26shows O-rings 1070' sealing both gaps 1130a and 1130b, such O-rings maynot be necessary, depending upon the electrostatic clamping forceinduced.

The plasma reactor provides a great improvement (by a factor of about 6in the case of the introduction of helium) in thermal conductivityacross the interface between heat-receiving elements of the reactoreither inside the chamber (such as chamber liners, disposable siliconrings) and outside the chamber (such as window electrodes, side walls)and a cooling plate or cold sink. As a result, the automated control oftemperature of many critical parts of the plasma reactor is improved toa new capability exceeding that of the prior art. The inventionaccomplishes this in one or a combination of two characteristic modes atthe various interfaces: (a) the introduction of a thermally conductivegas into the interface and (b) the introduction of a thermallyconductive solid layer in the interface. This, in combination withefficiently controlled heating of the same elements, permits accuratefeedback control of the temperature of each such element thus heated andcooled.

In selecting the heat transfer materials and/or physical dimensions ofthe reactor, the cooling conductance required (G) is determined asfollows:

    G=total maximum internal heat load (watts)/Delta-T1 (degree C)

where Delta-T1=Difference between heat sink temperature and minimumwindow/electrode temperature.

Alternatively, if the heat transfer materials and physical dimensionshave already been chosen, then the required heat sink temperature may betrivially calculated by rearranging the above equation for Delta-T1 asfunction of G.

Heating power is then determined as follows:

    P=total external heating power required (watts) delivered to control surface,

    P=(G*Delta-T2)-Pmin

where:

G is the cooling conductance from above (in watts/degree C),

Delta-T2=Difference between heat sink temperature and maximumwindow/electrode temperature

Pmin is the minimum internal heat load on the window/electrode.

EXAMPLE 1

The window/electrode 52 and the heat transfer rings 75 are integrallyformed as a monolithic piece, and the window/electrode 52 is a flatcircular disk 12.81 inches in diameter and 0.85 in thick. Formedintegrally with the window/electrode 52 is an array of four concentriccylindrical heat transfer rings (75) 2" high of the following inside andoutside diameters:

1. outer heat transfer ring--12.80" outside dia., 10.79" inside dia.,

2. middle heat transfer ring--9.010" outside dia., 7.595" inside dia.,

3. inner heat transfer ring--5.715" outside dia., 3.940" inside dia.,

4. center heat transfer ring--2.260" outside dia., 0.940" inside dia.

The window/electrode 52 and integral array of concentric cylindricalheat transfer rings 75 are fabricated together from a single ingot ofpolycrystalline silicon with the following thermal and electricalproperties:

    ______________________________________                                        Doping level:   10.sup.14 /cm.sup.3, boron or phosphorous                     Thermal conductivity:                                                                         80 watt/meter*Kelvin                                          Electrical resistivity:                                                                       from 20 to 100 ohm*cm                                         Specific Heat:  0.7 joule/gram*Kelvin                                         Density:        2.3 gram/cm.sup.3                                             ______________________________________                                    

A plurality of 750 watt@120 volt rms tungsten filament lamps 76 areemployed. The number of lamps is selected based on measured 73%efficiency (output power/ac input power) and on 400 watt@80 volt rmsmaximum operating level (for long lamp life). Two heat zones areemployed, those on the outer circle comprise one zone (outer), and thoseon the inner circle and at the center comprise the second (inner) zone.Each zone has its own temperature measurement (a type-K thermocouplespring loaded against the window/electrode surface) and its own outputtransducer (a phase-angle controller). The lamps, manufactured bySylvania, are deployed as follows:

15 lamps on a 13.55" diameter circle, equal angular spacing (24degrees);

15 lamps on a 6.655"diameter circle, equal angular spacing (24 degrees);

1 lamp on central axis.

The outer lamp circle is surrounded on the outside by a cylindricalpolished aluminum reflector that is integral with the heat sink 74.

The outer solenoid antenna 90 is 4 turns comprised of 3/16" diameterwater cooled copper tubing insulated with 1/4" outside diameter teflontubing yielding coil 1" in height and 10" mean diameter, wound asdescribed in the above-referenced parent application.

The inner solenoid antenna 42 is 4 turns comprised of 3/16" diameterwater cooled copper tubing insulated with 1/4" outside diameter teflontubing yielding coil 1" in height and 3.25 mean diameter, wound asdescribed in the above-referenced parent application.

The heat sink plate 74 is a water cooled aluminum plate maintained at 75degree C by a closed loop heat exchanger using a 50/50%water/ethylene-glycol mixture at a flow rate of 2 gallons per minute.The heat sink 74 houses lamp sockets and provides cooling for the lamps76 required due to inherent lamp losses to socket (approximately 27%).The heat sink plate 74 includes feed-through for the inner and outersolenoidal antennas 42, 90. The heat sink 74 also functions as a groundplane for the antennas 42, 90. The heat sink plate 74 includes O-ringgrooves to accommodate 0.139 inch diameter, 30 durometer soft O-ringsdeployed just inside the outer diameter of each heat transfer ring 75and just outside the inner diameter of each heat transfer ring 75. Theheat sink 74 is mounted on top of the integral array of concentriccylindrical heat transfer rings 75. Surface roughness of both surfaces(the bottom of the heat sink 74 and the top of heat transfer rings 75)is less than a micro-inch. Flatness of each surfaces is less than 0.0005inch. The effective gap between the bottom of the heat sink and the topof the heat transfer rings is less than 0.001 inch.

EXAMPLE 2

The window/electrode 52 and the heat transfer rings 75 are separatepieces formed of different materials. The window/electrode 52 is a flatcircular disk 14.52 inches in diameter and 0.85 inches thick. A separatearray of 4 concentric cylindrical heat transfer rings 75 2" high of thefollowing inside and outside diameters is placed in between the heatsink plate and the window electrode:

1. outer heat transfer ring--12.70" outside dia., 10.67" inside dia.,

2. middle heat transfer ring--8.883"outside dia., 7.67" inside dia.,

3. inner heat transfer ring--5.576" outside dia., 3.920" inside dia.,

4. center heat transfer ring--2.080" outside dia., 1.050" inside dia.

The window/electrode 52 is fabricated from a single ingot ofpolycrystalline silicon with the following thermal and electricalproperties:

    ______________________________________                                        Doping level:   10.sup.14 /cm.sup.3, boron or phosphorous                     Thermal conductivity:                                                                         80 watt/meter*Kelvin                                          Electrical resistivity:                                                                       20-100 ohm*cm                                                 Specific Heat:  0.7 joule/gram*Kelvin                                         Density:        2.3 gram/cm.sup.3                                             ______________________________________                                    

The array of concentric cylindrical heat transfer rings 75 arefabricated from SiC (silicon carbide) with the following thermal andelectrical properties:

    ______________________________________                                        Thermal conductivity:                                                                           130 watt/meter*Kelvin                                       Electrical resistivity:                                                                         10.sup.5 ohm*cm                                             Specific Heat:    0.655 joule/gram*Kelvin                                     Density:          3.2 gram/cm.sup.3                                           ______________________________________                                    

A plurality of 750 watt@120 volt rms tungsten filament lamps areemployed. The number of lamps is selected based on measured 73%efficiency (output power/ac input power) and 400 watt@80 volt rmsmaximum operating level (for long lamp life). Two heat zones areemployed, those on the outer circle comprise one zone (outer), and thoseon the inner circle and at the center comprise the second (inner) zone.Each zone has its own temperature measurement (a type-K thermocouplespring loaded against the window/electrode surface) and its own outputtransducer (a phase-angle controller). The lamps 76, manufactured bySylvania, are deployed as follows:

15 lamps on 13.55" diameter circle, equal angular spacing (24 degree);

15 lamps on 6.626" diameter circle, equal angular spacing (24 degree);

1 lamp on central axis.

The outer lamp circle is surrounded on the outside by a cylindricalpolished aluminum reflector that is integral with the heat sink.

The outer solenoid antenna 90 is four turns comprised of 3/16" diameterwater cooled copper tubing insulated with 1/4" outside diameter teflontubing yielding coil 1" in height and 10" mean diameter, wound asdescribed in the above-referenced parent application.

The inner solenoid antenna 42 is four turns comprised of 3/16" diameterwater cooled copper tubing insulated with 1/4" outside diameter teflontubing yielding coil 1" in height and 3.25 mean diameter, wound asdescribed in the above-reference parent application.

The heat sink plate 74 is a water cooled aluminum plate maintained at 75degrees C by a closed loop heat exchanger using a 50/50%water/ethylene-glycol mixture at a flow rate of 2 gallons per minute.Heat sink houses lamp sockets and provides cooling for the lamps,required due to inherent lamp losses to socket (approximately 27%). Theheat sink plate 74 includes feed-through for the aforementioned innerand outer solenoidal antennas 42, 90. The heat sink 74 also functions asa ground plane for the antennas. The heat sink plate 74 and thewindow/electrode 52 include O-ring grooves to accommodate 0.139 inchdiameter, 30 durometer soft O-rings deployed just inside the outerdiameter of each heat transfer ring 75 and just outside the innerdiameter of each heat transfer ring 75. The heat sink 74 is mounted ontop of the array of concentric cylindrical heat transfer rings 75.Surface roughness of all surfaces (bottom of the heat sink and top ofthe heat transfer rings, bottom of the heat transfer rings and top ofthe window/electrode) is less than a micro-inch. Flatness of eachsurface is less than 0.0005 inch. The effective gap between the bottomof the heat sink and the top of the heat transfer rings is less than0.001 inch. The effective gap between the bottom of the heat transferrings and the top of the window/electrode is less than 0.001 inch.

DETAILED DESCRIPTION RELATING TO THE PRESENT INVENTION

Removable Plasma Confinement Magnet Modules:

Referring now to FIG. 27, the plasma confinement magnets 80, 82protecting the pumping annulus 60 may each be encased in a modular(removable) magnet liner module. Thus, a magnet liner module 2010 holdsthe plasma confinement magnet 80 while a magnet liner module 2020 holdsthe plasma confinement magnet 82. Each magnet liner module 2010, 2020 ispreferably formed of a non-magnetic metal such as aluminum. The siliconceiling 52 rests on the liner module 2010 and the liner module 2010rests on the chamber side wall or body 50. An RF gasket 2012 and anO-ring 2014 are pressed between the liner module 2010 and the ceiling52. Another RF gasket 2016 and another O-ring 2018 are pressed betweenthe liner module 2010 and the chamber body 50. Referring to FIG. 28,each liner module 2010, 2020 has an opening or rectangular-shapeddepression 2030 in which the magnet (e.g., the magnet 80) resides. Themagnet 80 is bonded to the outward-facing surface of the opening 2030 bya bonding layer 2040 (which may be an epoxy material, for example)between the magnet 80 and the magnet liner module. The magnet 80 isprotectively sealed inside the opening 2030 by an aluminum cover 2050which can be laser welded or E-beam welded to the magnet liner module soas to seal the opening. This forms a welding layer 2060 between thecover 2050 and the liner module. The liner modules 2010, 2020 are placedon the interior walls of the pumping annulus 60 so that the magnets 80,82 are as close as possible to their regions of interaction with theplasma. One advantage of this embodiment is that the magnets 80, 82,although at a minimum distance from their plasma interaction regions,are protected from the plasma by being sealed inside their respectiveliner modules 2010, 2020. Another advantage is that the magnets arethermally coupled to cooled bodies (i.e., the chamber walls) by contactof the thermally conductive (aluminum) liner modules with the walls, sothat the magnets 80, 82 are cooled. This enables the plasma confinementmagnets to be maintained well below their Curie temperature andtherefore remain effective. For this purpose, in addition to the coolantpassages 74a through the cooling plate 74, additional coolant passages2070 can be provided in the chamber walls near the areas of contact withthe plasma confinement magnet liner modules 2010, 2020. To furtherenhance heat transfer from the magnet liner module to the chamber wall,each liner module 2010, 2020 may be fastened to the adjoining chamberwall by a fastener 2080. One feature of the magnet liner modules 2010,2020 is their easy removability from the chamber assembly for easycleaning.

In addition to protecting the pump annulus 60 by the plasma confinementmagnet pair 80, 82, the reactor may have a wafer slit valve 2082 whichcan be protected by another pair of plasma confinement magnets 2084,2086 encased in a similar pair of plasma confinement magnet linermodules 2088, 2090 each employing the features discussed above withreference to FIG. 28.

The plasma confinement magnet pairs can be employed to prevent plasmaleakage through any gap in the physical barrier (chamber wall) such asthe wafer slit valve, the gas inlet to the chamber, the pumping annulus,windows of the chamber or even the chamber wall itself. One example ofhow plasma leakage through gas inlets of the chamber can be prevented byplasma confinement magnets is illustrated in FIG. 27 for an overheadcenter gas feed 2092. The center gas feed 2092 accommodates a linermodule 2094 holding at least a pair of plasma confinement magnets 2096a,2096b facing one another across the center gas feed 2092. Alternatively,the liner module 2094 can be divided into two separable modules, eachholding one of the pair of plasma confinement magnets 2096a, 2096b. Thecenter gas feed liner module 2094 can be aluminum, although one optioncould be to employ silicon in the liner module 2094 for compatibilitywith the silicon ceiling 52. Each orifice or gas inlet of the reactorcan have a similar plasma confinement magnet liner module.

Instead of placing the center gas feed plasma confinement magnet insidea liner module within the ceiling, the magnets could be placed on top ofthe ceiling without using any liner module.

The liner modules referred to herein may not necessarily by liners ofthe chamber (e.g., removable pieces covering the chamber interiorsurfaces) but may instead simply serve as protective housings for theplasma confinement magnets without serving as liners.

The magnetic orientations of the plasma confinement magnet pairsreferred to above may be in accordance with any of the optionsillustrated in FIGS. 31A-31E, corresponding to the disclosure of one ofthe above-referenced co-pending applications, namely U.S. Ser. No.08/597,577.

Overcoming Non-Uniform Heating/Cooling of Ceiling:

Referring again to FIG. 27, the heat transfer from the ceiling 52 to thecold plate 74 through each thermally conductive ring 75 depends upon thethermal resistance across the gap 74' between the cooling plate 74 andthe thermally conductive ring 75. This resistance predominantly dependsupon the gap 74' which in turn depends upon surface flatness and theforce with which the ring 75 is held against the cooling plate 74.Unless the thermal resistances across all of the gaps 74' between thethermally conductive rings 75 and the cooling plate 74 are at leastnearly equal, heat transfer to the cooling plate 74 from different onesof the concentric thermally conductive rings 75 will be different.Because different areas of each of the rings 75 contact different areasof the ceiling 52, the disparity in heat transfer by the different rings75 produces a spatially non-uniform distribution of heat transfer acrossthe surface of the ceiling 52. Thus, assuming uniform heating of theceiling 52 by the distributed heater lamps 72, the non-uniformdistribution of heat transfer across the ceiling 52 will producetemperature differences across the ceiling 52, a significant problem. Itseems nearly impossible to avoid such a problem: a fairly uniformtemperature distribution across the 15 inch diameter ceiling 52 wouldrequire the gap between the cooling plate 74 and the rings 75 to bemaintained within a tolerance of one to two tenths of a mil (1/1000inch) across the entire diameter of the cooling plate (where the gap isfilled with air). In reality, with silicon-carbide materials, thetolerance is no better than two to three tenths and with aluminummaterials the tolerance is no better than 5 tenths or more. Therefore,depending upon how tightly the cooling plate 74 and the thermallyconductive rings 75 are fastened together, the ceiling 52 can experiencean excessive temperature difference across its diameter.

What is needed is an interface between the cooling plate 74 and eachthermally conductive ring 75 which permits the cold plate 74 to behinged upwardly from the thermally conductive rings 75 (without havingto break any electrical or gas or coolant connections or couplings) andwhich provides uniform thermal contact resistance. Such rapidremovability is necessary for periodic maintenance or replacement of theceiling. Therefore, attempting to provide an interface having uniformthermal contact resistance by bonding the thermally conductive rings 75to the cold plate 74 is not a viable solution, as this would preventremovability. Uniformity of thermal contact resistance could be enhancedby employing a soft aluminum material in the gap 74', but this wouldrequire too great a compressive force between the cold plate 74 and thethermally conductive rings 75 (because of the large variation in thewidth of the gap 74' across the cold plate 74). Uniformity of contactresistance could be enhanced by employing a thermally conductive greasein the gaps 74', but this would be too messy and risk high contaminantlevels in the plasma process.

We have found that employing a thermally conductive elasticallydeforming material such as Grafoil as a thermally conductive layer 3010within the gap 74' compensates for the poor gap tolerances referred toabove in that it provides relatively uniform thermal contact resistanceacross the diameter of the ceiling 52 without requiring excessivecompressive force between the cold plate 74 and the thermally conductiverings 75. (Grafoil is a product sold by UCAR Carbon Co., Inc., P.O. Box94364, Cleveland, Ohio 44101). The required compressive force is reducedby reducing the thickness of the elastically deformed thermallyconductive layer 3010 placed inside the gap 74'. (The layer 3010 iselastically deformed by the compression between the cold plate 74 andthe thermally conductive rings 75. However, the thickness of the layer3010 cannot be reduced beyond a minimum thickness necessary to enablethe elastically deformable thermally conductive material of the layer3010 to compensate for a large tolerance in gap thickness. Thus, thereis a tradeoff between thickness and stiffness. To optimize thistradeoff, we have found a preferred thickness of the elasticallydeformed thermally conductive layer 3010 to be within a range of about0.04 to 0.16 inch and more preferably within a range of about 0.06 to0.125 inch.

One problem we have encountered with the elastically deformed thermallyconductive layer 3010 is that it absorbs RF power from the inductivecoils 42, 90 and shunts the heat to the cooling plate 74. We have solvedthis problem by placing an electrically conductive layer 3020 betweenthe thermally conductive layer 3010 and the thermally conductive ring 75which reflects the RF inductive field from the coils 42, 90, and therebyprevents absorption of RF power by the thermally conductive layer 3010.We prefer the electrically conductive layer 3020 be aluminum and have athickness on the order of approximately 1-10 mils and preferably betweenabout 2-3 mils. Conveniently, the supplier of Grafoil referred to abovesupplies Grafoil tape with an aluminum coating on one side of theGrafoil tape. A suitable material other than aluminum can be used as thereflective layer 3020, such as copper, nickel, silver or gold forexample. Such a material should meet the dual requirement of sufficientheat conductivity and high reflectance to the inductive RF field fromthe coils 42, 90.

The advantages of the preferred material, aluminum-layered Grafoil tape,for the thermally conductive layer 3010, is that it meets therequirement for a thermally conductive material which is elasticallydeformable, thin and readily separable from both the cooling plate 74and the thermally conductive ring 75, while its aluminum coatingprovides a good reflector to the RF inductive field.

In accordance with one possible alternative, in addition to placing anelastically deformed thermally conductive layer 3010 between the coolingplate 74 and the thermally conductive rings 75, thermal contactresistance across the gap 75' between each thermally conductive ring 75and the semiconductor ceiling 52 could be improved employing a similarlayer of elastically deformable thermally conductive material in the gap75' between the ceiling 52 and each thermally conductive ring 75. Thus,an elastically deformed thermally conductive layer 3035 (such asGrafoil) can be placed in the gap 75' between each thermally conductivering 75 and the ceiling 52. However, the semiconductor ceiling 52 andthe thermally conductive rings 75 preferably constitute a single modularassembly so that the rings 75 preferably are not separable from theceiling 52, because the rings 75 and the ceiling 52 are bonded togetherto optimize heat transfer.

Modularity and Enhanced Productivity

Modularity (separability) is important for ease of maintenance. An upperassembly 3040 including the cooling plate 74, the source power coils 42,90 and the heater lamps 72 is separately hingeable from a lower assembly3050 including the thermally conductive rings 75 and the semiconductorceiling 52. The lower assembly 3050 itself is hingeable from thechamber. The separability of the upper assembly 3040 and the lowerassembly 3050 permits the semiconductor ceiling 52 to be replacedwithout breaking fluid and electrical connections. Such replacement isnecessary after processing on the order of 100,000 wafers. Theseparability of the lower assembly 3050 (leaving the upper assemblyattached to it) permits access to the plasma confinement magnet modules2010, 2020 for removal and cleaning as well as to the chamber interiorsurfaces for wiping, without having to break fluid or electricalconnections. This may be required after processing on the order of 3,000to 4,000 wafers.

Not shown in the drawing of FIG. 27 are the hinging apparatus (forhinging the cooling plate 74 and for hinging the ceiling 52) and theclamping apparatus for clamping the cooling plate 74 onto the thermallyconductive rings 75 and for clamping the silicon ceiling 52 onto themagnet liner module 2010.

Electrostatic Chuck with Semiconductor Lift Pins:

In accordance with another aspect of the invention, an electrostaticchuck is enhanced with a feature which eliminates the necessity ofdischarging the wafer through the plasma when de-chucking the wafer.Conventionally, to de-chuck a wafer from an electrostatic chuck, thefollowing steps must be performed:

(1) release the He gas vacuum between the wafer and the electrostaticchuck;

(2) ground the back side of the electrostatic chuck;

(3) wait until the wafer discharges through the plasma, and then removethe wafer.

The problem with this method is that a wafer having a thick dielectriccoating slows down the discharge of the wafer through the plasma, orprevents a thorough discharge, so that excessive force is required toremove the wafer. Or, if too much charge has accumulated on the wafer,the wafer cannot be thoroughly discharged within a practical amount oftime.

The present invention overcomes the foregoing problems with conventionalelectrostatic chucks by providing grounded semiconductor pins or liftpins within the chuck that are raised to contact the backside of thewafer whenever it is desired to remove or de-chuck the wafer. The waferis discharged by ohmic contact or tunneling or surface leakage from thebackside of the wafer to the semiconductor pins. Referring to FIG. 27,the electrostatic chuck 54 holds the wafer 56 down by electrostaticforce through an electric field applied across an electrostatic chuckdielectric layer 54a between the wafer 56 and the chuck 54. Theelectrostatic force may be produced by charging the electrostatic chuck54 by temporarily connecting it to a voltage source, as indicated in thedrawing. The electrostatic chuck 54 is enhanced with the addition of oneor more plural semiconductor lift pins 4010 extending upwardly throughthe chuck 54 toward the backside of the wafer. A lift spider 4020supporting the opposite ends of the semiconductor pins 4010 is moved byan actuator 4030 up or down so as to move the semiconductor lift pins4010 up or down as desired. In order to de-chuck the wafer, thesemiconductor lift pins are grounded and the actuator 4030 moves thelift spider 4020 upwardly until the semiconductor lift pins contact thebackside of the wafer. The wafer then discharges very rapidly, afterwhich the wafer can be removed. The advantage is that there is little orno risk of wafer breakage during de-chucking because the wafer isthoroughly discharged regardless of whether the wafer has a thickdielectric coating or has a large accumulated charge. Preferably, thesemiconductor lift pins 4010 are silicon carbide, although they may beany suitable semiconductor material such as silicon, for example. Thesilicon carbide material may be formed by chemical vapor deposition. Asingle such pin may suffice in many cases.

The advantage of semiconductor grounding or lift pins over metal pins isthat the conductivity of a metal is so great that a resistor must beemployed to avoid arcing at the wafer backside surface, and even withsuch a resistor a metal pin provides points along its length for arcingor gas breakdown and for shunting currents resulting therefrom to otherplaces in the reactor. Moreover, metal pins are more subject to wear. Incontrast, semiconductor (e.g., silicon carbide) lift pins have a higherelectrical resistivity and therefore do not pose as great a risk forarcing and are more durable.

Electrostatic Chuck Silicon Carbide Collar

The electrostatic chuck 54 may be further enhanced with the addition ofa silicon carbide collar 4050 around its periphery. The silicon carbidecollar 4050 may be formed by chemical vapor deposition. The siliconcarbide collar 4050 is between the electrostatic chuck 54 and the heatedsilicon ring 62. The collar 4050 preferably is co-extensive in heightwith the electrostatic chuck 54 as shown in the drawing. However, thecollar 4050 may, in some embodiments, extend above the plane of thechuck 54 so as to cover the edge of the wafer supported on the chuck 54.

The semiconductor collar 4050 prevents etching of the electrostaticchuck which otherwise could lead to contamination and force expensivefrequent replacement of the electrostatic chuck. Moreover, thesemiconductor materials of the collar 4050 is less susceptible toetching (or etches more slowly) than other materials, such as quartz forexample.

Slit in Heated Silicon Ring

The heated silicon ring 62 may be enhanced by the provision of a radialslit 4060 therethrough, best shown in FIG. 29. The slit 4060 permitsgreater thermal expansion of the silicon ring 62 without breakage.

RF Induction Coil with Azimuthally Uniform Number of Windings

As previously disclosed in the co-pending application, an inductiveantenna may be formed of multiple co-planar circular windings (asdistinguished from a single helical winding). Each winding is connectedto its neighbor by a step in the conductor between adjacent planes. Thisis illustrated in FIG. 30, in which stacked multiple planar circularwindings 5010 start with one end 5020 descending from an adjacent planeand terminate with the other end 5040 descending into the next adjoiningplane. The ascending and descending ends 5020, 5040 define a step 5060in the monolithic conductor 5065 from which the multiple windings 5010are formed. The number of windings in the stack is inherentlynon-uniform because of the step 5060 in the conductor 5065. This is due,in part, to the abrupt departure of the top winding 5010a from the stackby its sharp turn from a direction parallel to the planes of thewindings 5010 to a perpendicular direction. Such an abrupt departurecreates a deficiency in the number of windings stacked bottom to top,giving rise to the non-uniformity.

In accordance with the present invention, this non-uniformity iscompensated by running the bottom return leg 5070 of the conductor 5065along an upwardly ascending arcuate path (e.g., a circular path)extending from one end 5060a to the other end 5060b of the step 5060 inthe conductor 5065. The radius of the circular path of the bottom returnleg 5070 is such that it contributes a maximum inductance near the stepend 5060a where it is most nearly parallel to the planes of the windings5010 and contributes a minimum inductance near the other step end 5060bwhere it is most nearly perpendicular to the planes of the windings5010. The smooth transition in the inductance contribution of the bottomreturn leg 5070 corresponds to the transition along the length of thestep 5060 in the conductor 5065 from one end 5060a having the leastnumber of stacked windings (absent the return leg 5070) to the other end5060b having the greatest number of stacked windings. This providesoptimum uniformity in the effective number of windings.

DETAILED DESCRIPTION

FIG. 32 shows a perspective view of a chamber body 4002 supporting,through a hinge axis 4004, a hinge assembly, which in turn provides apivotable support for a chamber roof assembly 4000. Utilities suchcooling liquid, instrument wiring, process gasses, and process powerwiring are run through flexible connections, such as 4006, which do notneed to be disturbed during the normal raising hinging of the chamberroof assembly 4000 to access the inside of the process chamber 4008.Once the chamber is open as shown in FIG. 32, the upper and lowerchamber liners 4011, 4012 can easily be removed as well as serviceprovided to components in the chamber which might require servicing(e.g., heat lamps, silicon ring, or e-chuck). Once the chamber roofassembly 4000 has been raised those components can easily be removed,replaced, and the chamber returned to service quickly. The bottom sideof the chamber roof 4014 can be seen in FIG. 32. The edge of the chamberroof 4014 is captured by a lift ring 4009 which is fixed to the chamberroof assembly 4000. Details of this connection are discussed below.

FIG. 33 shows a perspective view of an alternate service scenario, wherethe chamber roof assembly 4000, is raised, but the chamber roof 4014 isleft in place. In this view can be seen the heat transfer rings 4016,4018, 4021, 4022. These heat transfer rings are extensions of roof 4014,preferably are thermally conductive members and are preferably of asilicon bearing material. Advantageously, the rings may be prefabricatedand fixed to the top of the roof 4014. Thus, the roof 4014 and heattransfer rings 4016, 4018, 4021, 4022 comprise a chamber roof subunit.Since all chamber topside elements except the chamber roof subunit arepivoted away, this configuration leaves the chamber roof subunitunrestricted and immediately removable from the chamber body 4002 forcleaning or replacement.

A cold plate subassembly or subunit 4024 mounts all of the heating andcooling, plasma inducing, and sensing elements for roof assembly 4000,as may best be seen in FIGS. 33 and 37. A series of heat lamps, e.g.4026, 4028, 4031, in a concentric array are mounted through the coldplate 4024 to face the top of the chamber roof 4014. Two spring loadedtemperature sensors 4032, 4034 mounted in highly reflective guide tubesextend from the bottom of the cold plate 4024, toward the chamber roof4014 and contact it to sense its temperature when the chamber roofassembly 4000 is in a closed position. Two RF coils 4036, 4038 held in aseries of brackets, e.g., 4040, 4042, when roof assembly 4000 is loweredinto place extend between the heat transfer rings 4016, 4018 and 4021,4022, respectively, to closely approach the chamber roof 4014. The coilsare hollow so that cooling liquid circulates through them. The brackets,e.g., 4040, 4042, engaging and locating the coils are connected to thecold plate 4024. The brackets are made of a high temperature tolerantand RF transparent material, such as a high temperature plastic.

FIG. 34 shows a top view of the cold plate 4024, showing locations wherethe heater lamps are mounted generally equally spaced in a circularpattern around the center of the cold plate. A heater lamp 4031 and theheater lamps in a first ring 4044 of heater lamps (including for exampleheater lamp 4028 and the center lamp 4031) comprise a first heatingzone. An extra hole, e.g., 4046, through the cold plate 4024 isprovided, between the heater lamps to provide for mounting oftemperature sensors and/or access to the top of the chamber roof.Rotatably and linearly compliant spring loaded sensors are use to assurea good thermal contact. So that readings from the thermal sensors are asaccurate as possible and are not distorted by exposure to the heat lampsmounted in the adjacent mounting holes, e.g. 4032, the thermal sensorsare mounted within highly reflective and thermally conductive housingswhich extend from the cold plate into close proximity with the top ofthe chamber roof 4014, thus shielding the end of the sensor and itswiring from direct exposure to the radiation from the heat lamps. Thecold plate 4024, to which the thermally conductive housings, e.g. 4042,4034 are mounted conducts heat away rapidly through the cooling mediacirculating through it.

An outer heat lamp circle 4054 locates the heater lamps for an secondheating zone. Again, within this outer circle 4054 of mounting holes,the heater lamps, e.g., 4026, are mounted approximately equally spacedfrom one another, and an extra opening, e.g., 4056 is provided formounting of temperature sensors or other access to the top of thechamber roof 4014. The first heating zone is controlled separately fromthe second heating zone, as already described previously.

The cold plate 4024 is mounted to the chamber roof assembly 4000 througha series of three support locations 4062, 4064, 4066 which are oriented120 degree from each other from the center of the cold plate 4024. Thecold plate is not rigidly fixed to the chamber roof assembly, but isattached through a spring and stop linkage as will be described below.

Coil feed through openings 4068, 4070 in the cold plate are provided sothat the two end connections of both the inner coil 4038 and the outercoil 4036 are fed through their respective feed through opening, 4068,4070. The two end connectors of each coil each are connected to anelectrical (RF) power source and to a liquid cooling circuit (the coilsbeing constructed, for example of a hollow tubing.

The cold plate also includes peripheral slots 4073, 4075, 4077, whichprovide a passage for thumbscrews which can selectively clamp thechamber roof assembly 4000 to the upper lift ring 4009 (not shown inFIG. 34). The lift ring/thumbscrew arrangement is described below. Theperipheral slots are located 120 degrees from one another and are 60degrees offset from the support locations mounting the cold plate 4024to the chamber roof assembly 4000.

FIG. 35 is a schematic cross sectional view of the sealing andconnection arrangement between the chamber body 4002 and the roofassembly 4000 including the chamber roof 4014. A lower liner module 4072is located in the periphery of the chamber body 4002. An upper linermodule 4074 acts to bridge and seal the gap between the chamber body4002 and the chamber roof 4014, and includes features to create a vacuumlimit for the processing chamber. The vacuum limit being the envelopeinside of which a process chamber vacuum is maintained and outside ofwhich ambient atmospheric pressure is present. In this configuration thevacuum limit is defined at the O-rings 4076, 4078, sealing between thepieces. The upper liner module 4074 has a "Z" shaped cross section. Theouter flange 4080 overlapping the top of the upper edge of the lowerbody member 4002. The outer flange 4080 includes a groove for the O-ring4078 and a groove for receiving a compliant electrical connecting ring4082 (RF gasket). The inner flange 4084 also has the O-ring 4076 and agroove for receiving a compliant electrical connecting ring 4087 (RFgasket). The chamber roof is preferably made of silicon, or some othersimilarly brittle material, although it may also be made of any othermaterial suitable for a chamber plasma processing enclosure, chamberroofs of silicon based or other brittle need to be protected from stressconcentrations which may tend to crack such materials. In sealing of thebottom of the chamber roof 4014 to the top of the inner flange 4084 ofthe upper liner module 4074 it is preferred that there be no directcontact between the aluminum material of the 4074 and the siliconmaterial of the chamber roof 4014. The sealing O-ring 4076 protrudesbeyond the surface of the inner flange 4084 and supports the chamberroof 4014 above the top surface of the inner flange, with a gaptherebetween. In the event that the O-ring were to fail through forexample oxidation due to an over temperature condition, or if theinstallation of the O-ring were to be overlooked by a technician, thealuminum surface of the inner flange 4084 of the upper liner modulecould directly contact the bottom surface of the chamber roof flange4014a, which will cause high stress concentrations between the surfacesand possible cracking. To safeguard against such an occurrence a polymerbased (nylon like) high temperature tolerant "L" shaped insert 4086 isprovided at the flange surface adjacent to the O-ring and RF gasket4076, 4086 grooves.

In FIG. 35, the lift ring 4009 is shown floating. It is located abovethe outer flange 4080 of the upper liner module 4074 and below a supportflange 4001 of the chamber roof assembly 4000. A thumbscrew 4088 havinga large shank 4090, a narrow shank 4092, a threaded section 4094, andenlarged end 4096, is located in a thumbscrew opening 4098 of thechamber roof assembly 4000. The thumbscrew 4088 is spring loaded to moveupwards by a spring 4100 (only a portion of which is shown--it abuts thebottom of the enlarged end 4096 and the top of the support flange 4001.When the thumbscrew 4088 is pushed down it threaded section 4094 engagesa threaded opening 4102 in the lift ring 4009. When the thumbscrew 4088is tightened the lift ring 4009 is brought into a tightly clampedrelationship with the support flange 4001 (See FIG. 38). A compliantinsert 4104 (plastic, nylon or other similar material with a hightemperature tolerance) is fixed to the lift ring 4009, by screws (notshown) and prevents the aluminum lift ring 4009, from directlycontacting the silicon chamber roof 4014 or its lift flange 4014b. Thethumbscrew assembly as described above is situated to pass through aperipheral slot, e.g., 4075, as viewed in FIG. 34.

FIG. 35 also pictures a close-up of the construction of the chamber roof4014 and its interface with the cold plate 4024. The chamber roof 4014is bonded to the heat transfer rings, e.g., 4022, through a thermallyconductive adhesive or bond which generally provides a permanent bondbetween each of the heat transfer rings and the top of the chamber roof4014. The top of each of the heat transfer rings, e.g., 4022, is coveredwith a compliant thermally conductive heat transfer material, e.g.,Grafoil--4108, which is in turn pressed (clamped) against the top of theheat transfer rings by the cold plate 4024. As can be seen in FIG. 35,the cold plate 4024 supports the heat lamps, e.g. 4026, an outsidebarrier wall (reflector) 4106, the induction coils, e.g., theouter--4036, and the coil support brackets, e.g., 4042.

FIG. 36 shows a schematic cross section of a set of spring memberssuspending the cold plate 4024 from the support flange 4001 of thechamber roof assembly 4000 and urging the cold plate 4024 into contactwith the chamber roof subunit. The clamping members are shown onopposite sides of the Figure for clarity, even though they are actuallyoriented 120 degrees from one another. The cold plate 4024 includes aclamping flange 4110 having holes at support locations, e.g., 4064 inFIG. 34, through which a clamping/guide stud 4112 is positioned. Theclamping/guide stud 4112 is fixed to the support flange 4001 of thechamber roof assembly 4000. An alignment portion 4114 of theclamping/guide stud 4112 extends below the support flange 4001 andcooperates with the upper liner module 4074 to provide a circularreference alignment. The alignment portion 4114, may be offset from thelongitudinal axis of said clamping/guide stud 4112 to help prevent itrotation when the nut 4116 at the top of the clamping/guide stud 4112 istightened.

The spring support of the cold plate 4024, to the roof in one mode andaway from the roof in another mode is described as follows. Uniformtemperature across the chamber roof 4014, requires that there be agenerally uniform supply and removal of thermal energy across the withof the chamber roof 4014. The supply is done by controlling theintensity of heat/lamps, e.g., 4026, whose radiative effect is minimallyaffected by small changes in distance between the lamp and the roof ofthe chamber as the mechanism for heat transfer is not dependent onmaintaining a bond between adjacent members. This is in contrast to thecooling mode associated with temperature control of the chamber roof4014, where the heat removal path is by conduction through the heattransfer rings 4016, 4018, 4021, 4022, through a gap, e.g., 4020 shownby the arrows 4118, 4119, through a compliant thermal transfer materialplaced in the gap, but not shown in FIG. 36 and to the cold plate 4024.The gap 4020 and others between the top of the heat transfer rings 4016,4018, 4021, 4022, are partially filled with a compliant heat transfermaterial. One such material is Grafoil, earlier discussed. Such amaterial has a low crush resistance, and the uniformity of thermal heattransfer across such an interface is partially dependent on the clampingpressure and surface contact pressure between adjacent members.Premature crushing or distortion of parts of the compliant material maycreate gaps or distortions in the material which greatly affect thethermal conduction and greatly distort the temperature distribution(uniformity ) across the chamber roof. To avoid such anomalies, astructure which uniformly maintains the contact between members acrossthe gap 4020 containing the compliant thermal transfer material isprovided. With a uniform thickness of compliant thermal transfermaterial in each of the gaps between the tops of the heat transfer ringsand the bottom of the cold plate 4024, both of which have beenplanarized to a very flat tolerance, e.g., as done by a lathe cut, thecold plate 4024 is gently positioned over the rings of the roof andguided by the clamping/guide studs, e.g., 112. The chamber roof assembly4000 and chamber body 4002 are clamped in a closed relationship by alatch, e.g., a portion of which is shown as 4124, on the opposite sidefrom the hinge axis 4004 of the chamber assembly. A release spring 4120provides a separating force between the support flange 4001 of thechamber roof assembly and the clamping flange 4112 of the cold plate4024. The release spring 4120 supports the cold plate 4024 separatedfrom the heat transfer rings of the chamber roof 4014. The releasespring 4120 provides an upward separating force to lift the cold platewhen the clamping springs are released. A clamping spring 4122 ispositioned on top of the clamping flange 4112 of the cold plate 4024 andacts between the bottom of the nut 4116 and the top of the clampingflange 4112, as the nuts, e.g., 4116, around the perimeter of thechamber are progressively and incrementally tightened to increasinglyhigher torque ratings. The initial tightening causes the force of therelease spring to be overcome so that the cold plate 4024 descendsevenly to contact and press against the top of the compliant heattransfer material in the gaps between the heat transfer rings and thecold plate. Then because the clamping spring 4122 is a much moresubstantial spring, having a higher spring rate, with a large clampingdistance, the force of release spring 4120 is overcome and uniformcrushing of the compliant heat transfer material over the roof takesplace as the nuts on the various clamping/guide studs, e.g., 4112, aretightened to a maximum clamping force value. The thermal connectionbetween the chamber roof 4014 and the cold plate is there therebyassured, until the clamping force urging the cold plate 4024 toward thechamber roof is removed.

One configuration where a release of the clamping force would occurwould be when the chamber roof 4014 is supported by the chamber body4002 and the latch holding the chamber roof assembly 4000 and chamberbody 4002 together, is released. The spring force clamping the coldplate 4024 to the top of the thermal transfer rings, e.g., 4016, isreleased and the cold plate separates from the chamber roof as thechamber roof assembly rotates about the hinge axis 4004 of the hingeassembly. The cold plate and all the structures supported by it areremoved from the proximity of the chamber roof and the coils and otherelements on the bottom of the cold plate can be easily accessed.Similarly, the chamber roof is free unfettered by connection to anyutilities and can be removed and replaced in a straightforward liftingoperation.

FIG. 38 shows a schematic cross sectional view of the cold plate 4024clamped to the top of the chamber roof 4014. The lift ring 4009 isclamped tightly to the support flange 4001 of the chamber roof assembly4000 by thumbscrews, e.g., 4088. In this configuration, even though thelift ring 4009 is tightly clamped to the support flange 4001, it isloosely situated around the outside of the chamber roof 4014, and a ringgap 4126. A small fraction of an inch exists between the top of thecompliant insert 4104 of the lift ring 4009, and the bottom of thechamber roof lift flange 4014b. Upon release of the latch 4124, thechamber roof assembly 4000 will again start to rise away from thechamber body 4002 as the clamping spring 4122 presses the cold plate4024 downward and toward the support flange 4001.

FIG. 39 shows that the vertical movement of the chamber roof assembly isstopped as the upper edge of the lift ring assembly comes into contactwith the lift flange 4014b of the chamber roof 4014, eliminating thering gap 4126 that formerly existed there. The lift ring 4009 thenprevents further extension of the clamping springs. e.g., 4122, and ahigh level of clamping force across the compliant heat transfer materialin the gap 4020 is maintained, while the vertical dimension of the gapis unaffected. The clamping spring 4122 has been extended by the formervertical dimension of the ring gap 4026, which is a very small changeconsidering that the clamping spring has an installed length of severalinches. The heavy black arrows 4128, 4130, 4132, 4134 show the forcesand their approximate origin, clamping the chamber roof 4014 and coldplate together.

FIG. 40 shows an example of the configuration of FIG. 39 being furtherhinged upwards toward an orientation as shown in FIG. 32.

The vertically compliant and clamping arrangement of the cold plate mustbe accommodated by all of the utility connections to the cold plate. Thewiring connections to the heat lamps and the cooling liquid hoses to thecooling fluid passages (fluid circulating lines) in the cold plate arewell understood in the art. The high power RF supply connectors supplypower to the RF coils 4036, 4038. Each coil has two end connections,e.g., 4136, 4138, which are connected to a cooling fluid source or loopthrough flexible piping or tubing 4140, 4142, which preferably iselectrically nonconducting. In addition electrical power is supplied tothe coil ends by clamping a set of vertically flexibly mounted bus bars4144, 4146 (RF supply connectors) to the side of the coil tubes throughwhich the cooling liquid is flowing. As the coils move up and down withthe cold plate 4024, the connections to utilities are not affected.Those connections which require replacement are equipped with quickdisconnect connectors to facilitate quick and easy maintenance.

A workpiece (substrate) 4148 supported on a generally flat pedestal 4150as previously discussed extensively in the specification above, islocated opposite the chamber roof 4014.

While the invention has been described with regards to specificembodiments, those skilled in the art will recognize that changes can bemade in form and detail without departing from the spirit and scope ofthe invention.

What is claimed is:
 1. A chamber for processing a workpiece having amulti-mode chamber access configuration comprising:a chamber bodysubunit including a pedestal defining a generally flat surface formounting workpiece to be processed; a chamber roof subunit removably andsealingly engageable upon said chamber body subunit, said roof subunitincluding a chamber roof extending in spaced relationship to and alongsaid pedestal workpiece surface when engaged upon said chamber bodysubunit, said roof subunit including at least one separator memberextending laterally away from said roof and away from said pedestal; acold plate subunit removably engageable with said at least one separatormember so as to be positioned in a spaced relationship from said chamberroof; a coil supported from said cold plate subunit so as to bepositionable adjacent said chamber roof, said coil accepting RF powerand capable of causing a plasma to be established in a gas within saidchamber by induction; a hinge assembly peripherally mounting both saidchamber roof subunit and said cold plate subunit so as to move said coldplate subunit independently of or together with said chamber roofsubunit about a hinge axis of rotation; whereby in a first mode, bothchamber roof and cold plate subunits may be pivoted as a single assemblyaway from the chamber body subunit for access to the interior of thechamber, and in a second mode, the cold plate subunit may be pivotedaway from the chamber body subunit independently of the chamber roofsubunit, to allow the chamber roof subunit to be accessed or removedfrom the chamber body subunit and cold plate subunit easily andimmediately as to allow access to cold plate and coil componentsnormally facing the roof subunit.
 2. The chamber as in claim 1, in whichsaid cold plate subunit is adapted to accept fluid circulation lines forcooling and to mount RF supply connectors to enable RF power to betransmitted to said coil.
 3. The chamber as in claim 1, in which saidcold plate subunit includes an array of heat lamps extending toward saidchamber roof when the cold plate and roof subunits are in engagementwith the chamber body subunit.
 4. The chamber as in claim 1, in whichthe cold plate subunit mounts a plurality of said coils.
 5. The chamberof claim 1, which includes a plurality of said at least one separatormember in concentric arrays.
 6. The chamber of claim 5 which furtherincludes a plurality of coils said coils being distributed and supportedso as to lie within or outside of said concentric arrays.
 7. The chamberof claim 5, in which said separator members are of a thermallyconductive material.
 8. The chamber of claim 1, in which said chamberroof is a silicon material.
 9. The chamber of claim 1, in which saidseparator members are a silicon material.
 10. The chamber of claim 1, inwhich a thermally compliant layer is positioned between said at leastone separator member and said cold plate and is compressed therebetweenfor improved thermal transmissibility.
 11. A configuration for a plasmachamber comprising:a plasma processing chamber roof sealed to andcreating a portion of a vacuum limit of the plasma processing chambertogether with a chamber body assembly; a cold plate disposedapproximately parallel to and offset from said roof; a plurality ofthermally conductive members creating a thermal bridge between the roofand the cold plate; wherein the thermal bridge is detachably connectedto either said cold plate or said roof, such that when said cold plateis separated from said roof, the roof and the space therebetween isaccessible.
 12. The configuration for a plasma chamber as in claim 11,wherein the roof is made of a silicon based material.
 13. Theconfiguration for a plasma chamber as in claim 12, wherein the roof ismade of a semiconducting material.
 14. The configuration for a plasmachamber as in claim 13, wherein the roof is made of silicon carbide. 15.The configuration for a plasma chamber as in claim 11, whereinseparation between the roof and the cold plate is as a result of thecold plate being fixed to a hinge mechanism which cause the cold plateas it is separated from said roof to hinge about a hinge axis, whereinthe hinge axis is fixed to said chamber body.
 16. The configuration fora plasma chamber as in claim 11, wherein said series of thermallyconductive members includes a ring.
 17. The configuration for a plasmachamber as in claim 16, wherein said ring is fixed to said roof and ismated to said cold plate through a compliant heat transfer material. 18.The configuration for a plasma chamber as in claim 17, wherein saidcompliant heat transfer material is Grafoil.
 19. The configuration for aplasma chamber as in claim 11, wherein a coil which induces the plasmain the processing chamber is fixed to and supported by the cold plate.20. The configuration for a plasma chamber as in claim 11, wherein a setof heaters/lamps disposed to heat the chamber roof are supported by thecold plate.
 21. The configuration for a plasma chamber as in claim 19,wherein a set of heaters/lamps disposed to heat the chamber roof aresupported by the cold plate.
 22. The configuration for a plasma chamberas in claim 11, wherein a thermal sensor for sensing the temperature ofthe chamber roof is supported by the cold plate.
 23. The configurationfor a plasma chamber as in claim 11, wherein said thermally conductivemembers are urged into contact with said cold plate by a set of springmembers.
 24. The configuration for a plasma chamber as in claim 16,wherein said thermally conductive members are urged into contact withsaid cold plate by a set of spring members.
 25. The configuration for aplasma chamber as in claim 17, wherein said thermally conductive membersare urged into contact with said cold plate by a set of spring members.26. The configuration for a plasma chamber as in claim 18, wherein saidthermally conductive members are urged into contact with said cold plateby a set of spring members.
 27. The configuration for a plasma chamberas in claim 11, wherein a lift ring can be selectively attached to anchamber roof assembly, said lift ring when engaged with said chamberroof assembly causing said roof to move with said cold plate as a unit.28. The configuration for a plasma chamber as in claim 27, wherein saidcold plate is fixed through the chamber roof assembly to a hingemechanism which causes the cold plate, roof, and chamber roof assemblyas a unit to hinge about a hinge axis, wherein the hinge axis is fixedto said chamber body.
 29. The configuration for a plasma chamber as inclaim 28, wherein utilities supplied to and supported by said coldplate, are configured so that they do not have to be disconnected beforethe cold plate, roof and chamber roof assembly is hinged about the hingeaxis.
 30. The chamber as in claim 1, wherein said chamber roof assemblyis movable between first and second positions.
 31. The chamber as inclaim 30, wherein the movement of said chamber roof is as a result of ahinge assembly supported on the chamber body.
 32. The configuration fora plasma chamber as in claim 11, wherein the body chamber also includesa hinge mechanism having a hinge axis around which chamber roof assemblyis fixed and pivots.
 33. An easy-maintenance vacuum processing chambercomprising:a chamber body assembly; a chamber roof assembly, includingachamber roof sealingly engageable with said chamber body to form avacuum enclosure; a utilities support assembly positionable over saidroof including a heat exchanging surface, and a coil accepting RF energyand supported in electrical isolation upon said surface; and a thermallytransmissive spacer positionable between said heat exchanging surfaceand roof, supporting said assembly upon said roof and body and providinga heat transmission path between roof and heat exchanging surface; saidutilities support assembly being removeable from said body separatelyfrom said roof, said roof being thereupon removeable for servicing ofthe roof or chamber interior without disassembly of heat exchanging andRF functions.
 34. A vacuum processing chamber as in claim 33, in whichsaid utilities support assembly comprises a cold plate.
 35. A vacuumprocessing chamber as in claim 34, in which said support assemblyincludes heat bulbs directing heat energy towards said roof.
 36. Achamber as in claim 33 which further includes a hinge assembly pivotallymounting said utilities support assembly upon said chamber body assemblyso as to permit said utilities support assembly to be pivoted away fromsaid chamber body without disturbing said roof.
 37. A chamber as inclaim 33 in which said utilities support assembly and said roof arereleasably joined together and pivoted from said chamber body as anunit.
 38. A chamber as in claim 33 in which said thermally transmissivemember is bonded to said roof so as to form a roof subunit, and in whichsaid utilities support assembly is removable separately from said roofsubunit.
 39. A chamber as in claim 38 in which a plurality of saidthermally transmissive members are provided.
 40. A chamber as in claim33 in which said coil is supported upon said heat exchanging surface soas to be positioned between and spaced from said plurality of thermallytransmissive members.
 41. A chamber as in claim 39 which furtherincludes a compressible layer of thermally transmissive material betweensaid heat exchanging surface and thermally transmissive members.
 42. Achamber as in claim 41 which further includes at least one springtensioner urging said utilites support assembly and said thermallytransmissive members together with said roof into contact.